The problem is that builds are not just a concatentation of CPU-bound things. There's more to a build than that. An interesting item came up recently. On Win

The problem is that builds are not just a concatentation of CPU-bound things. There's more to a build than that. An interesting item came up recently. On Windows 10 there's a problem with highly parallel builds that is down to the fact that process exit cleanup is serialized inside the GDI on a lock that also needs to be taken during message input. Combine that with a build that splits things out into lots of compilation units that are all built in parallel using a process each, and fun ensues. Ironically, it means that during the build you are not able to get stuck into anything else with a GUI. (-: * https://randomascii.wordpress.com/2017/07/09/24-core-cpu-and-i-cant-move-my-mouse/ https://randomascii.wordpress.com/2017/07/09/24-core-cpu-and... (https://news.ycombinator.com/item?id=14733829 https://news.ycombinator.com/item?id=14733829)