diff --git a/ReStore/SSWDBOwnedCollectionSpec.cls b/ReStore/SSWDBOwnedCollectionSpec.cls
index a9497a5..a95e134 100644
--- a/ReStore/SSWDBOwnedCollectionSpec.cls
+++ b/ReStore/SSWDBOwnedCollectionSpec.cls
@@ -47,12 +47,21 @@ deleteQuery
 		yourself!
 
 elementsIn: aCollection notIn: anotherCollection
-
-	^aCollection reject: [ :each | anotherCollection identityIncludes: each]!
+	| testAgainst |
+	"For small collections, the IdentitySet is actually slower, so just stick with the original collection in that common case."
+	testAgainst := anotherCollection size < 10
+				ifTrue: [anotherCollection]
+				ifFalse: [anotherCollection asIdentitySet].
+	^aCollection reject: [:each | testAgainst identityIncludes: each].!
 
 hasCollection: updatedCollection anyAdditionsOrRemovalsFrom: originalCollection
-
-	^updatedCollection size ~= originalCollection size or: [updatedCollection anySatisfy: [ :each | (originalCollection identityIncludes: each) not]]!
+	| testAgainst |
+	updatedCollection size = originalCollection size ifFalse: [^true].
+	"For small collections, the IdentitySet is actually slower, so just stick with the original collection in that common case."
+	testAgainst := originalCollection size < 10
+				ifTrue: [originalCollection]
+				ifFalse: [originalCollection asIdentitySet].
+	^updatedCollection anySatisfy: [:each | (testAgainst identityIncludes: each) not].!
 
 orderingSpecs