Changing from a static lib to a dll slows compilation

Question

Using VS2003, we migrated our C++ application from a quasi-monolitic to a dll distributed application.

In the process, the compilation time of our complete application (exe and dll) slowed down considerably. Certain files (going from a static lib to a dll) get 3~4 times slower to compile (no change of code).

I made a test on our largest dll (~5.5MB), I removed all __declspec(dllexport) statement from that dll. (ie the dll exports no methods). This compile time went from 6m27s to 2m17s on a Core2-Duo 2.3GHz.

My questions are: What is so heavy about the export statement? Is it possible to reduce the compile time without reducing the number of exported methods?

Cyril109