The first time I had to compile a Linux kernel for Android, it took only a few seconds (on the ridiculously overpowered "build machine" my employer supplied). I was sure I must have done something wrong, but no, that was the entire build. It takes longer for Android to reboot than it does to build the kernel.

It does feel like there's something seriously wrong with the massive C++ codebases we use these days for key infrastructure like browsers, and the massive compilation times we put up with.