Asp.net 4.5 "multi-core jitting" not working
===

I'd like to take advantage of the new multi-core jitting feature in .net 4.5.

 - My web.config is set to targetFramework="4.5"
 - The application pool framework in IIS is set to v4.0 (from what I understand, that is correct)
 - My processor is an i7 with 4 cores (or 8 with hyperthreading) - http://ark.intel.com/products/52214/

But it doesn't seem to have decreased the JIT compilation time (based on performance profiling), and I can see no evidence of any *.prof files being created in ASP.NET Temporary Files.

How can I track down the reason for this?