Comparing C/C++ unity build with regular build on a large codebase (2024) (hereket.com)

A developer benchmarks “unity builds” for a large C/C++ project by adapting the Inkscape build into a custom script and then merging source files into unified translation units. The study reports that a unity-style approach reduced single-core compilation time to about 3 minutes versus roughly 34–35 minutes for a clean regular CMake/Make build, with the final merged compilation units taking only 10 object-like outputs. While parallel builds with tools like ccache remain faster for day-to-day development, the results suggest substantial per-translation-unit speedups from compiling fewer, larger units.