DynamicMethod is much slower than compiled IL function

Question

I wrote a simple object copier that copies public properties. I can\'t figure out why the Dynamic method is a lot slower than the c# version.

Durations

C# me

Answer 1

This problem was introduced by changes made in .NET Framework 4.0. I found a solution posted by user "Alan-N" on CodeProject.

The big slowdown in execution time is caused when the DynamicMethod gets associated with a "system-provided, fully trusted, security-transparent assembly," which happens if you use the DynamicMethod(string, Type, Type[], bool) constructor. It appears that .NET 4 is doing more security checks than the previous versions although I have no insight into, or explanation for, what is actually going on.

Associating the DynamicMethod with a Type (by using the DynamicMethod(string, Type, Type[], Type, bool) constructor instead; notice the additional Type-valued parameter, 'owner') completely removes the speed penalty.

There are some notes on MSDN which may be relevant (if only I could understand them!):

• DynamicMethod Constructor (String, Type, Type[], Boolean)
• Security Issues in Reflection Emit