Consider caching the result of FSharpType.IsRecord and FSharpType.IsUnion

[baronfel]

Per the implementation here and here, these functions have to use reflection to get type custom attributes, deconstruct them, and do some additional processing. Would it make sense to build a dict of hash(type.FullName) -> bool and check that before delegating to the underlying function for the IsRecord/IsUnion checks that are done as part of CanConvert for the serializers?

[Tarmil]

Good question, I don't know if CanConvert is called repetitively or only during warmup.

[baronfel]

From what I was reading in the JsonPropertyInfo-createing code, CanConvert will eventually be called for every property of every type that you want to serialize.