>The application suffers from a lot of the dreaded 'C0005' errors. Whether that's a result of instantiating uncompiled classes is another story. Insofar as performance tests are concerned, both compiled and uncompiled classes run at the same speed, but the time to instantiate uncompiled libraries seems to take longer. If you could explain why this is so, I'd appreciate it.

Generally, it is faster for VFP to resolve a class reference inside the same exe than to find it in the external file system. That they actually run at the same speed is expected.

BTW, Compile/ uncompiled is really not the right term for what is happening here. Even external vcxs are already compiled, or they would not run; it's just that they are not included in the exe. Included/excluded might be a more accurate way to put it.