I once tried to compile nheko, a Matrix client written in C++ and Qt. It makes heavy use of boost and compiling it crashed my system when I tried to compile using 2 jobs or more because it would eat up all my ram (6GB available at that time). Factor in the 2 seconds per compilation unit and it takes ages to compile. I managed to compile the native webrtc library with 8 jobs faster than this bare bones chat client on the same computer.