Writing Class in App_Code or in a Class Library, Which one works faster ?

Hi,
Suppose i have to create some dynamic controls. For that i want to do it in either of two ways- one writing my logic in a Class in  the same project's App_Code folder. Another way i can do is writing my logic in a separate Class library project. That project will generate a MSIL (dll) file that i can add reference to my project.
I think that second option will work faster since MSIL is already cooked up for my main project. Otherwise following the first option will create MSIL each time project runs .I am not sure whether i am right or not.
Any suggestion please..
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