diff --git a/src/System.CommandLine.Tests/ArgumentTests.cs b/src/System.CommandLine.Tests/ArgumentTests.cs
index 937c6d4505..388224ec19 100644
--- a/src/System.CommandLine.Tests/ArgumentTests.cs
+++ b/src/System.CommandLine.Tests/ArgumentTests.cs
@@ -278,7 +278,7 @@ public void Option_ArgumentResult_parentage_to_root_symbol_is_set_correctly_when
                     .Parent
                     .Parent
                     .Should()
-                    .BeAssignableTo<CommandResult>()
+                    .BeOfType<CommandResult>()
                     .Which
                     .Command
                     .Should()
@@ -340,7 +340,7 @@ public void Command_ArgumentResult_Parent_is_set_correctly_when_token_is_implici
                 argumentResult
                     .Parent
                     .Should()
-                    .BeAssignableTo<CommandResult>()
+                    .BeOfType<CommandResult>()
                     .Which
                     .Command
                     .Should()
diff --git a/src/System.CommandLine.Tests/CommandTests.cs b/src/System.CommandLine.Tests/CommandTests.cs
index e40bb071f8..9974354874 100644
--- a/src/System.CommandLine.Tests/CommandTests.cs
+++ b/src/System.CommandLine.Tests/CommandTests.cs
@@ -46,7 +46,7 @@ public void Outer_command_is_identified_correctly_by_Parent_property()
                 .CommandResult
                 .Parent
                 .Should()
-                .BeAssignableTo<CommandResult>()
+                .BeOfType<CommandResult>()
                 .Which
                 .Command
                 .Name
diff --git a/src/System.CommandLine.Tests/ParserTests.cs b/src/System.CommandLine.Tests/ParserTests.cs
index 6deae54c4c..127f228cdf 100644
--- a/src/System.CommandLine.Tests/ParserTests.cs
+++ b/src/System.CommandLine.Tests/ParserTests.cs
@@ -668,7 +668,7 @@ public void When_options_with_the_same_name_are_defined_on_parent_and_child_comm
             result.CommandResult
                   .Parent
                   .Should()
-                  .BeAssignableTo<CommandResult>()
+                  .BeOfType<CommandResult>()
                   .Which
                   .Children
                   .Should()
@@ -697,7 +697,7 @@ public void When_options_with_the_same_name_are_defined_on_parent_and_child_comm
             result.CommandResult
                   .Parent
                   .Should()
-                  .BeAssignableTo<CommandResult>()
+                  .BeOfType<CommandResult>()
                   .Which
                   .Children
                   .Should()
@@ -1008,7 +1008,7 @@ public void Option_and_Command_can_have_the_same_alias()
                   .CommandResult
                   .Parent
                   .Should()
-                  .BeAssignableTo<CommandResult>()
+                  .BeOfType<CommandResult>()
                   .Which
                   .Children
                   .Should()
diff --git a/src/System.CommandLine/Argument.cs b/src/System.CommandLine/Argument.cs
index 67784e8bd3..42d5de1d7f 100644
--- a/src/System.CommandLine/Argument.cs
+++ b/src/System.CommandLine/Argument.cs
@@ -113,7 +113,7 @@ private protected override string DefaultName
         /// <returns>Returns the default value for the argument, if defined. Null otherwise.</returns>
         public object? GetDefaultValue()
         {
-            return GetDefaultValue(new ArgumentResult(this, null));
+            return GetDefaultValue(new ArgumentResult(this, null!, null));
         }
 
         internal abstract object? GetDefaultValue(ArgumentResult argumentResult);
diff --git a/src/System.CommandLine/ParseResult.cs b/src/System.CommandLine/ParseResult.cs
index 1616690e49..dca48e3457 100644
--- a/src/System.CommandLine/ParseResult.cs
+++ b/src/System.CommandLine/ParseResult.cs
@@ -15,14 +15,14 @@ namespace System.CommandLine
     public class ParseResult
     {
         private readonly IReadOnlyList<ParseError> _errors;
-        private readonly RootCommandResult _rootCommandResult;
+        private readonly CommandResult _rootCommandResult;
         private readonly IReadOnlyList<Token> _unmatchedTokens;
         private Dictionary<string, IReadOnlyList<string>>? _directives;
         private CompletionContext? _completionContext;
 
         internal ParseResult(
             Parser parser,
-            RootCommandResult rootCommandResult,
+            CommandResult rootCommandResult,
             CommandResult commandResult,
             Dictionary<string, IReadOnlyList<string>>? directives,
             List<Token> tokens,
diff --git a/src/System.CommandLine/Parsing/ArgumentResult.cs b/src/System.CommandLine/Parsing/ArgumentResult.cs
index 949b9eba72..dfe89c4cb4 100644
--- a/src/System.CommandLine/Parsing/ArgumentResult.cs
+++ b/src/System.CommandLine/Parsing/ArgumentResult.cs
@@ -16,7 +16,8 @@ public sealed class ArgumentResult : SymbolResult
 
         internal ArgumentResult(
             Argument argument,
-            SymbolResult? parent) : base(parent)
+            SymbolResultTree symbolResultTree,
+            SymbolResult? parent) : base(symbolResultTree, parent)
         {
             Argument = argument ?? throw new ArgumentNullException(nameof(argument));
         }
@@ -110,7 +111,7 @@ Parent is { } &&
 
             if (Parent!.UseDefaultValueFor(argument))
             {
-                var argumentResult = new ArgumentResult(argument, Parent);
+                var argumentResult = new ArgumentResult(argument, SymbolResultTree, Parent);
 
                 var defaultValue = argument.GetDefaultValue(argumentResult);
 
diff --git a/src/System.CommandLine/Parsing/CommandResult.cs b/src/System.CommandLine/Parsing/CommandResult.cs
index dac4af0b37..645e7d0388 100644
--- a/src/System.CommandLine/Parsing/CommandResult.cs
+++ b/src/System.CommandLine/Parsing/CommandResult.cs
@@ -8,13 +8,14 @@ namespace System.CommandLine.Parsing
     /// <summary>
     /// A result produced when parsing a <see cref="Command" />.
     /// </summary>
-    public class CommandResult : SymbolResult
+    public sealed class CommandResult : SymbolResult
     {
         internal CommandResult(
             Command command,
             Token token,
+            SymbolResultTree symbolResultTree,
             CommandResult? parent = null) :
-            base(parent)
+            base(symbolResultTree, parent)
         {
             Command = command ?? throw new ArgumentNullException(nameof(command));
             Token = token ?? throw new ArgumentNullException(nameof(token));
@@ -33,7 +34,7 @@ internal CommandResult(
         /// <summary>
         /// Child symbol results in the parse tree.
         /// </summary>
-        public IEnumerable<SymbolResult> Children => GetChildren(this);
+        public IEnumerable<SymbolResult> Children => SymbolResultTree.GetChildren(this);
 
         internal sealed override int MaximumArgumentCapacity
         {
diff --git a/src/System.CommandLine/Parsing/OptionResult.cs b/src/System.CommandLine/Parsing/OptionResult.cs
index 60d7dfb849..acbe7db56d 100644
--- a/src/System.CommandLine/Parsing/OptionResult.cs
+++ b/src/System.CommandLine/Parsing/OptionResult.cs
@@ -15,9 +15,10 @@ public sealed class OptionResult : SymbolResult
 
         internal OptionResult(
             Option option,
+            SymbolResultTree symbolResultTree,
             Token? token = null,
             CommandResult? parent = null) :
-            base(parent)
+            base(symbolResultTree, parent)
         {
             Option = option ?? throw new ArgumentNullException(nameof(option));
             Token = token;
diff --git a/src/System.CommandLine/Parsing/ParseOperation.cs b/src/System.CommandLine/Parsing/ParseOperation.cs
index 34997725bb..da2381f23b 100644
--- a/src/System.CommandLine/Parsing/ParseOperation.cs
+++ b/src/System.CommandLine/Parsing/ParseOperation.cs
@@ -102,6 +102,12 @@ private void ParseCommandArguments(CommandNode commandNode, ref int currentArgum
 
                     if (currentArgumentCount < argument.Arity.MaximumNumberOfValues)
                     {
+                        if (CurrentToken.Symbol is null)
+                        {
+                            // update the token with missing information now, so later stages don't need to modify it
+                            CurrentToken.Symbol = argument;
+                        }
+
                         var argumentNode = new CommandArgumentNode(
                             CurrentToken,
                             argument,
diff --git a/src/System.CommandLine/Parsing/ParseResultExtensions.cs b/src/System.CommandLine/Parsing/ParseResultExtensions.cs
index e678e6b125..d4df35a870 100644
--- a/src/System.CommandLine/Parsing/ParseResultExtensions.cs
+++ b/src/System.CommandLine/Parsing/ParseResultExtensions.cs
@@ -159,7 +159,7 @@ private static void Diagram(
                     builder.Append("[ ");
                     builder.Append(symbolResult.Token().Value);
 
-                    foreach (SymbolResult child in symbolResult.GetChildren(symbolResult))
+                    foreach (SymbolResult child in symbolResult.SymbolResultTree.GetChildren(symbolResult))
                     {
                         if (child is ArgumentResult arg &&
                             (arg.Argument.ValueType == typeof(bool) ||
diff --git a/src/System.CommandLine/Parsing/ParseResultVisitor.cs b/src/System.CommandLine/Parsing/ParseResultVisitor.cs
index a4b89e8bf0..ed94ed50a6 100644
--- a/src/System.CommandLine/Parsing/ParseResultVisitor.cs
+++ b/src/System.CommandLine/Parsing/ParseResultVisitor.cs
@@ -14,17 +14,14 @@ internal sealed class ParseResultVisitor
         private readonly Parser _parser;
         private readonly List<Token> _tokens;
         private readonly string? _rawInput;
+        private readonly SymbolResultTree _symbolResultTree;
+        private readonly CommandResult _rootCommandResult;
 
         private Dictionary<string, IReadOnlyList<string>>? _directives;
         private List<Token>? _unmatchedTokens;
         private List<ParseError>? _errors;
-
-        private readonly Dictionary<Symbol, SymbolResult> _symbolResults = new();
-
         private List<ArgumentResult>? _argumentResults;
-
-        private RootCommandResult? _rootCommandResult;
-        private CommandResult? _innermostCommandResult;
+        private CommandResult _innermostCommandResult;
         private bool _isHelpRequested;
 
         internal ParseResultVisitor(
@@ -32,12 +29,18 @@ internal ParseResultVisitor(
             List<Token> tokens,
             List<string>? tokenizeErrors,
             List<Token>? unmatchedTokens,
-            string? rawInput)
+            string? rawInput,
+            CommandNode rootCommandNode)
         {
             _parser = parser;
             _tokens = tokens;
             _unmatchedTokens = unmatchedTokens;
             _rawInput = rawInput;
+            _symbolResultTree = new(_parser.Configuration.LocalizationResources);
+            _innermostCommandResult = _rootCommandResult = new CommandResult(
+                rootCommandNode.Command,
+                rootCommandNode.Token,
+                _symbolResultTree);
 
             if (tokenizeErrors is not null)
             {
@@ -53,8 +56,6 @@ internal ParseResultVisitor(
 
         internal void Visit(CommandNode rootCommandNode)
         {
-            VisitRootCommandNode(rootCommandNode);
-
             VisitChildren(rootCommandNode);
 
             Stop();
@@ -97,60 +98,46 @@ private void VisitInternal(SyntaxNode node)
 
         private void AddToResult(ArgumentResult result)
         {
-            if (_symbolResults.TryAdd(result.Argument, result))
+            if (_symbolResultTree.TryAdd(result.Argument, result))
             {
                 (_argumentResults ??= new()).Add(result);
             }
         }
 
-        private void VisitRootCommandNode(CommandNode rootCommandNode)
-        {
-            _rootCommandResult = new RootCommandResult(
-                rootCommandNode.Command,
-                rootCommandNode.Token,
-                _symbolResults,
-                _parser.Configuration.LocalizationResources ?? LocalizationResources.Instance);
-
-            _innermostCommandResult = _rootCommandResult;
-        }
-
         private void VisitCommandNode(CommandNode commandNode)
         {
             var commandResult = new CommandResult(
                 commandNode.Command,
                 commandNode.Token,
+                _symbolResultTree,
                 _innermostCommandResult);
 
-            _symbolResults.Add(commandNode.Command, commandResult);
+            _symbolResultTree.Add(commandNode.Command, commandResult);
 
             _innermostCommandResult = commandResult;
         }
 
         private void VisitCommandArgumentNode(CommandArgumentNode argumentNode)
         {
-            if (!(_symbolResults.TryGetValue(argumentNode.Argument, out var symbolResult)
+            if (!(_symbolResultTree.TryGetValue(argumentNode.Argument, out var symbolResult)
                     && symbolResult is ArgumentResult argumentResult))
             {
                 argumentResult =
                     new ArgumentResult(
                         argumentNode.Argument,
+                        _symbolResultTree,
                         _innermostCommandResult);
 
                 AddToResult(argumentResult);
             }
 
-            var token = argumentNode.Token.Symbol is null
-                            ? new Token(argumentNode.Token.Value, TokenType.Argument, argumentResult.Argument)
-                            : argumentNode.Token;
-
-            argumentResult.AddToken(token);
-
-            _innermostCommandResult?.AddToken(token);
+            argumentResult.AddToken(argumentNode.Token);
+            _innermostCommandResult.AddToken(argumentNode.Token);
         }
 
         private void VisitOptionNode(OptionNode optionNode)
         {
-            if (!_symbolResults.ContainsKey(optionNode.Option))
+            if (!_symbolResultTree.ContainsKey(optionNode.Option))
             {
                 if (optionNode.Option is HelpOption)
                 {
@@ -159,17 +146,18 @@ private void VisitOptionNode(OptionNode optionNode)
 
                 var optionResult = new OptionResult(
                     optionNode.Option,
+                    _symbolResultTree,
                     optionNode.Token,
                     _innermostCommandResult);
 
-                _symbolResults.Add(optionNode.Option, optionResult);
+                _symbolResultTree.Add(optionNode.Option, optionResult);
 
                 if (optionNode.Children is null) // no Arguments
                 {
                     if (optionResult.Option.Argument.HasCustomParser)
                     {
-                        ArgumentResult argumentResult = new (optionResult.Option.Argument, optionResult);
-                        _symbolResults.Add(optionResult.Option.Argument, argumentResult);
+                        ArgumentResult argumentResult = new (optionResult.Option.Argument, _symbolResultTree, optionResult);
+                        _symbolResultTree.Add(optionResult.Option.Argument, argumentResult);
                     }
                 }
             }
@@ -178,18 +166,19 @@ private void VisitOptionNode(OptionNode optionNode)
         private void VisitOptionArgumentNode(
             OptionArgumentNode argumentNode)
         {
-            OptionResult optionResult = (OptionResult)_symbolResults[argumentNode.ParentOptionNode.Option];
+            OptionResult optionResult = (OptionResult)_symbolResultTree[argumentNode.ParentOptionNode.Option];
 
             var argument = argumentNode.Argument;
 
-            if (!(_symbolResults.TryGetValue(argument, out SymbolResult? symbolResult)
+            if (!(_symbolResultTree.TryGetValue(argument, out SymbolResult? symbolResult)
                     && symbolResult is ArgumentResult argumentResult))
             {
                 argumentResult =
                     new ArgumentResult(
                         argumentNode.Argument,
+                        _symbolResultTree,
                         optionResult);
-                _symbolResults.TryAdd(argument, argumentResult);
+                _symbolResultTree.TryAdd(argument, argumentResult);
             }
 
             argumentResult.AddToken(argumentNode.Token);
@@ -235,7 +224,7 @@ private void Stop()
 
             ValidateCommandResult();
 
-            foreach (var symbolPair in _symbolResults)
+            foreach (var symbolPair in _symbolResultTree)
             {
                 if (symbolPair.Value is OptionResult optionResult)
                 {
@@ -245,7 +234,7 @@ private void Stop()
 
             if (_argumentResults is not null)
             {
-                ValidateAndConvertArgumentResults(_innermostCommandResult!.Command.Arguments, _argumentResults);
+                ValidateAndConvertArgumentResults(_innermostCommandResult.Command.Arguments, _argumentResults);
             }
         }
 
@@ -273,11 +262,12 @@ private void ValidateAndConvertArgumentResults(IList<Argument> arguments, List<A
                     var nextArgument = arguments[i];
                     var nextArgumentResult = new ArgumentResult(
                         nextArgument,
+                        _symbolResultTree,
                         _innermostCommandResult);
 
                     var previousArgumentResult = argumentResults[i - 1];
 
-                    var passedOnTokensCount = _innermostCommandResult?.Tokens.Count;
+                    var passedOnTokensCount = _innermostCommandResult.Tokens.Count;
 
                     ShiftPassedOnTokensToNextResult(previousArgumentResult, nextArgumentResult, passedOnTokensCount);
 
@@ -288,7 +278,7 @@ private void ValidateAndConvertArgumentResults(IList<Argument> arguments, List<A
                         AddToResult(nextArgumentResult);
                     }
 
-                    _symbolResults.TryAdd(nextArgumentResult.Argument, nextArgumentResult);
+                    _symbolResultTree.TryAdd(nextArgumentResult.Argument, nextArgumentResult);
                 }
 
                 if (commandArgumentResultCount >= argumentResults.Count)
@@ -331,17 +321,14 @@ void ShiftPassedOnTokensToNextResult(
                         break;
                     }
 
-                    if (_innermostCommandResult is not null)
-                    {
-                        next.AddToken(_innermostCommandResult.Tokens[j]);
-                    }
+                    next.AddToken(_innermostCommandResult.Tokens[j]);
                 }
             }
         }
 
         private void ValidateCommandResult()
         {
-            var command = _innermostCommandResult!.Command;
+            var command = _innermostCommandResult.Command;
 
             if (command.HasValidators && UseValidators(command, _innermostCommandResult))
             {
@@ -360,7 +347,7 @@ private void ValidateCommandResult()
                         var option = options[i];
                         if (option.IsRequired && (!checkOnlyGlobalOptions || (checkOnlyGlobalOptions && option.IsGlobal)))
                         {
-                            if (_rootCommandResult!.FindResultFor(option) is null)
+                            if (_rootCommandResult.FindResultFor(option) is null)
                             {
                                 AddErrorToResult(
                                     _innermostCommandResult,
@@ -422,7 +409,7 @@ private void ValidateArguments(IList<Argument> arguments, CommandResult innermos
 
         private void ValidateCommandHandler()
         {
-            if (_innermostCommandResult!.Command is not { Handler: null } cmd)
+            if (_innermostCommandResult.Command is not { Handler: null } cmd)
             {
                 return;
             }
@@ -471,7 +458,7 @@ private void ValidateAndConvertOptionResult(OptionResult optionResult)
                 }
             }
 
-            foreach (var pair in _symbolResults)
+            foreach (var pair in _symbolResultTree)
             {
                 if (object.ReferenceEquals(pair.Value.Parent, optionResult))
                 {
@@ -526,7 +513,7 @@ private void PopulateDefaultValues()
                     for (var i = 0; i < options.Count; i++)
                     {
                         Option option = options[i];
-                        Handle(_rootCommandResult!.FindResultFor(option), option);
+                        Handle(_rootCommandResult.FindResultFor(option), option);
                     }
                 }
 
@@ -536,7 +523,7 @@ private void PopulateDefaultValues()
                     for (var i = 0; i < arguments.Count; i++)
                     {
                         Argument argument = arguments[i];
-                        Handle(_rootCommandResult!.FindResultFor(argument), argument);
+                        Handle(_rootCommandResult.FindResultFor(argument), argument);
                     }
                 }
 
@@ -550,9 +537,9 @@ void Handle(SymbolResult? symbolResult, Symbol symbol)
                     case OptionResult o:
 
                         if (o.Option.Argument.ValueType == typeof(bool)
-                            && !_symbolResults.ContainsKey(o.Option.Argument))
+                            && !_symbolResultTree.ContainsKey(o.Option.Argument))
                         {
-                            _symbolResults.Add(o.Option.Argument, new ArgumentResult(o.Option.Argument, o));
+                            _symbolResultTree.Add(o.Option.Argument, new ArgumentResult(o.Option.Argument, _symbolResultTree, o));
                         }
 
                         break;
@@ -564,21 +551,23 @@ void Handle(SymbolResult? symbolResult, Symbol symbol)
 
                                 var optionResult = new OptionResult(
                                     option,
+                                    _symbolResultTree,
                                     null,
                                     commandResult);
 
-                                if (_symbolResults.TryAdd(optionResult.Option, optionResult))
+                                if (_symbolResultTree.TryAdd(optionResult.Option, optionResult))
                                 {
-                                    _symbolResults.Add(optionResult.Option.Argument, new ArgumentResult(optionResult.Option.Argument, optionResult));
+                                    ArgumentResult argumentResult = new (optionResult.Option.Argument, _symbolResultTree, optionResult);
+                                    _symbolResultTree.Add(optionResult.Option.Argument, argumentResult);
                                 }
 
                                 break;
 
                             case Argument { HasDefaultValue: true } argument:
 
-                                if (!_symbolResults.ContainsKey(argument))
+                                if (!_symbolResultTree.ContainsKey(argument))
                                 {
-                                    AddToResult(new ArgumentResult(argument, commandResult));
+                                    AddToResult(new ArgumentResult(argument, _symbolResultTree, commandResult));
                                 }
                                 
                                 break;
@@ -603,8 +592,8 @@ private void AddErrorToResult(SymbolResult symbolResult, ParseError parseError)
 
         public ParseResult GetResult() =>
             new(_parser,
-                _rootCommandResult ?? throw new InvalidOperationException("No root command was found"),
-                _innermostCommandResult ?? throw new InvalidOperationException("No command was found"),
+                _rootCommandResult,
+                _innermostCommandResult,
                 _directives,
                 _tokens,
                 _unmatchedTokens,
diff --git a/src/System.CommandLine/Parsing/Parser.cs b/src/System.CommandLine/Parsing/Parser.cs
index f20c9701e0..711e9e3e97 100644
--- a/src/System.CommandLine/Parsing/Parser.cs
+++ b/src/System.CommandLine/Parsing/Parser.cs
@@ -56,7 +56,8 @@ public ParseResult Parse(
                 tokens,
                 tokenizationErrors,
                 operation.UnmatchedTokens,
-                rawInput);
+                rawInput,
+                operation.RootCommandNode!);
 
             visitor.Visit(operation.RootCommandNode!);
 
diff --git a/src/System.CommandLine/Parsing/RootCommandResult.cs b/src/System.CommandLine/Parsing/RootCommandResult.cs
deleted file mode 100644
index f6c5461de8..0000000000
--- a/src/System.CommandLine/Parsing/RootCommandResult.cs
+++ /dev/null
@@ -1,45 +0,0 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
-// Licensed under the MIT license. See LICENSE file in the project root for full license information.
-
-using System.Collections.Generic;
-
-namespace System.CommandLine.Parsing
-{
-    internal sealed class RootCommandResult : CommandResult
-    {
-        private readonly Dictionary<Symbol, SymbolResult> _symbolResults;
-        private readonly LocalizationResources _localizationResources;
-
-        public RootCommandResult(
-            Command command,
-            Token token,
-            Dictionary<Symbol, SymbolResult> symbolResults,
-            LocalizationResources localizationResources) : base(command, token)
-        {
-            _symbolResults = symbolResults;
-            _localizationResources = localizationResources;
-        }
-
-        public override LocalizationResources LocalizationResources => _localizationResources;
-
-        public override ArgumentResult? FindResultFor(Argument argument)
-            => _symbolResults.TryGetValue(argument, out SymbolResult? result) ? (ArgumentResult)result : default;
-
-        public override CommandResult? FindResultFor(Command command)
-            => _symbolResults.TryGetValue(command, out SymbolResult? result) ? (CommandResult)result : default;
-
-        public override OptionResult? FindResultFor(Option option)
-            => _symbolResults.TryGetValue(option, out SymbolResult? result) ? (OptionResult)result : default;
-
-        internal override IEnumerable<SymbolResult> GetChildren(SymbolResult parent)
-        {
-            foreach (var pair in _symbolResults)
-            {
-                if (ReferenceEquals(parent, pair.Value.Parent))
-                {
-                    yield return pair.Value;
-                }
-            }
-        }
-    }
-}
diff --git a/src/System.CommandLine/Parsing/SymbolResult.cs b/src/System.CommandLine/Parsing/SymbolResult.cs
index 674c288523..6ab20d8151 100644
--- a/src/System.CommandLine/Parsing/SymbolResult.cs
+++ b/src/System.CommandLine/Parsing/SymbolResult.cs
@@ -3,7 +3,6 @@
 
 using System.Collections.Generic;
 using System.CommandLine.Binding;
-using System.Diagnostics;
 using System.Linq;
 
 namespace System.CommandLine.Parsing
@@ -13,10 +12,12 @@ namespace System.CommandLine.Parsing
     /// </summary>
     public abstract class SymbolResult
     {
+        internal readonly SymbolResultTree SymbolResultTree;
         private protected List<Token>? _tokens;
 
-        private protected SymbolResult(SymbolResult? parent)
+        private protected SymbolResult(SymbolResultTree symbolResultTree, SymbolResult? parent)
         {
+            SymbolResultTree = symbolResultTree;
             Parent = parent;
         }
 
@@ -46,7 +47,7 @@ private protected SymbolResult(SymbolResult? parent)
         /// <summary>
         /// Localization resources used to produce messages for this symbol result.
         /// </summary>
-        public virtual LocalizationResources LocalizationResources => GetRoot().LocalizationResources;
+        public LocalizationResources LocalizationResources => SymbolResultTree.LocalizationResources;
 
         internal void AddToken(Token token) => (_tokens ??= new()).Add(token);
 
@@ -55,36 +56,21 @@ private protected SymbolResult(SymbolResult? parent)
         /// </summary>
         /// <param name="argument">The argument for which to find a result.</param>
         /// <returns>An argument result if the argument was matched by the parser or has a default value; otherwise, <c>null</c>.</returns>
-        public virtual ArgumentResult? FindResultFor(Argument argument) => GetRoot().FindResultFor(argument);
+        public ArgumentResult? FindResultFor(Argument argument) => SymbolResultTree.FindResultFor(argument);
 
         /// <summary>
         /// Finds a result for the specific command anywhere in the parse tree, including parent and child symbol results.
         /// </summary>
         /// <param name="command">The command for which to find a result.</param>
         /// <returns>An command result if the command was matched by the parser; otherwise, <c>null</c>.</returns>
-        public virtual CommandResult? FindResultFor(Command command) => GetRoot().FindResultFor(command);
+        public CommandResult? FindResultFor(Command command) => SymbolResultTree.FindResultFor(command);
 
         /// <summary>
         /// Finds a result for the specific option anywhere in the parse tree, including parent and child symbol results.
         /// </summary>
         /// <param name="option">The option for which to find a result.</param>
         /// <returns>An option result if the option was matched by the parser or has a default value; otherwise, <c>null</c>.</returns>
-        public virtual OptionResult? FindResultFor(Option option) => GetRoot().FindResultFor(option);
-
-        internal virtual IEnumerable<SymbolResult> GetChildren(SymbolResult parent) => GetRoot().GetChildren(parent);
-
-        private SymbolResult GetRoot()
-        {
-            SymbolResult result = this;
-            while (result.Parent is not null)
-            {
-                result = result.Parent;
-            }
-
-            Debug.Assert(result is RootCommandResult);
-
-            return result;
-        }
+        public OptionResult? FindResultFor(Option option) => SymbolResultTree.FindResultFor(option);
 
         /// <inheritdoc cref="ParseResult.GetValue(Argument)"/>
         public T GetValue<T>(Argument<T> argument)
diff --git a/src/System.CommandLine/Parsing/SymbolResultExtensions.cs b/src/System.CommandLine/Parsing/SymbolResultExtensions.cs
index 443fdcfe62..86a573f269 100644
--- a/src/System.CommandLine/Parsing/SymbolResultExtensions.cs
+++ b/src/System.CommandLine/Parsing/SymbolResultExtensions.cs
@@ -13,7 +13,7 @@ internal static IEnumerable<SymbolResult> AllSymbolResults(this CommandResult co
 
             foreach (var item in commandResult
                                  .Children
-                                 .FlattenBreadthFirst(o => o.GetChildren(o)))
+                                 .FlattenBreadthFirst(o => o.SymbolResultTree.GetChildren(o)))
             {
                 yield return item;
             }
diff --git a/src/System.CommandLine/Parsing/SymbolResultTree.cs b/src/System.CommandLine/Parsing/SymbolResultTree.cs
new file mode 100644
index 0000000000..07ba985c7e
--- /dev/null
+++ b/src/System.CommandLine/Parsing/SymbolResultTree.cs
@@ -0,0 +1,42 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+
+namespace System.CommandLine.Parsing
+{
+    internal sealed class SymbolResultTree : Dictionary<Symbol, SymbolResult>
+    {
+        private readonly LocalizationResources _localizationResources;
+
+        internal SymbolResultTree(LocalizationResources localizationResources)
+        {
+            _localizationResources = localizationResources;
+        }
+
+        internal LocalizationResources LocalizationResources => _localizationResources;
+
+        internal ArgumentResult? FindResultFor(Argument argument)
+            => TryGetValue(argument, out SymbolResult? result) ? (ArgumentResult)result : default;
+
+        internal CommandResult? FindResultFor(Command command)
+            => TryGetValue(command, out SymbolResult? result) ? (CommandResult)result : default;
+
+        internal OptionResult? FindResultFor(Option option)
+            => TryGetValue(option, out SymbolResult? result) ? (OptionResult)result : default;
+
+        internal IEnumerable<SymbolResult> GetChildren(SymbolResult parent)
+        {
+            if (parent is not ArgumentResult)
+            {
+                foreach (KeyValuePair<Symbol, SymbolResult> pair in this)
+                {
+                    if (ReferenceEquals(parent, pair.Value.Parent))
+                    {
+                        yield return pair.Value;
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/src/System.CommandLine/Parsing/Token.cs b/src/System.CommandLine/Parsing/Token.cs
index 74dc55a63d..5e195215b1 100644
--- a/src/System.CommandLine/Parsing/Token.cs
+++ b/src/System.CommandLine/Parsing/Token.cs
@@ -46,7 +46,7 @@ internal Token(string? value, TokenType type, Symbol? symbol, int position)
         /// <summary>
         /// The Symbol represented by the token (if any).
         /// </summary>
-        internal Symbol? Symbol { get; }
+        internal Symbol? Symbol { get; set; }
 
         /// <inheritdoc />
         public override bool Equals(object? obj) => Equals(obj as Token);