Comment by wavemode

How much of the speedup you're seeing is modules, versus the inherent speedup of splitting and organizing your codebase/includes in a cleaner way? It doesn't sound like your project is actually compiling faster than before, but rather it is REcompiling faster, suggesting that your real problem was that too much code was being recompiled on every change (which is commonly due to too-large translation units and too many transitive dependencies between headers).