optimization suggestions

[kofifus]

Two ideas for optimization:

1. There is no need to add-to / find-in the InstanceExpressionCache cache (that is call ResolveInstance) when mutating a non nested member because we already have the instance in source in that case

2. Instead of creating & compiling an activator and a separate array of parameter resolvers (ActivationContext), create and cache a single lambda with an expression block:

(object instance, object val) => new TheType((MemberType)val, ((TheType)instance).LastName)

ie

(object x, object v) => new Employee((String)v, ((Employee)x).LastName)

This means you don't need to loop over the members if you had a cache hit, this also makes it easy to add a desirable feature where you can mutate multiple members with a single ctor call

Hope this helps
(you can see these ideas in practice here)