>I am working on an application where the developer is using several modules. The application is made up of many apps and a main exe. None of the classlibs are compiled. Instead they are distributed with the application and called as needed. The argument for not compiling the classes is that there is no appreciable performance gain, and the apps need access to the class libs. (Never mind that SET CLASSLIB TO cLib IN cEXE can be used here.)
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Actually, they are compiled, but you have excluded them from the .EXE so that they can be deployed externally. You could actually deploy the VCX/VCT pairs without the source code - simply clear the Methods field after having compiled the classlib - the object code is still there in the ObjCode field.

>I have always compiled all my clasess into my exe and have realized an enormous speed gain. Can anyone point me to some information that would enlighten me further on this topic?

Including the classlibs in the .EXE may improve overall system performance in several ways; it requires fewer files to be open at any instant in time, there are fewer directory entries which reduces the directory search overhead, and your app is less subject to the woes of a mismanaged search path. Keeping them separate makes it easier to update them without sending out one huge file easier, but it also makes you more subject to accidental versioning issues when one library gets out of step with the rest of the application. I find that my clients prefer that I exclude the Forms and Reports at a minimum, so that they can easily make minor changes or creeb a bit of code from my stuff. If the apps were going to be marketed as a shrink-wrapped product targeted at the typical end-user, the single .EXE looks prefereable.