VS 16.5 Tooling Performance

[cartermp]

This is an overarching issue that we're using to track F# tooling performance in VS up to VS 16.5. I expect these to positively impact other F# editors. Much of this work is actually in the compiler, as some things that are fine in a command-line scenario end up costing us dearly in a tooling scenario.

These are all filed based on data gathered from ETL traces with a solution loaded into Visual Studio, or are related to an issue where data was gathered in this way and determined to also be relevant. other issues labeled Tenet-Performance that are not listed here are not necessarily gathered in this way.

• Fixed LOH byte array allocations in the IDE from metadata #7971- LOH byte array allocations in the IDE from metadata
• Char array and String LOH allocations for UnicodeFileAsLexbuf #7973 - Char array and String LOH allocations for UnicodeFileAsLexbuf
• TcSymbolUseData array LOH allocations #7983 - TcSymbolUseData array LOH allocations
• [Performance] Use TokenTup object pool to reduce allocations in LexFilter #8058- Use TokenTup object pool to reduce allocations in LexFilter
• Use for..in..do instead of List.iter to prevent function allocations #8175 - Use for..in..do instead of List.iter to prevent function allocations (~2.5% of sample allocations come from function objects)

[cartermp]

All other tracking issues: #6866