They are still used in some places. But they have some downsides: Precompiled headers don't play nicely with distributed compilation or shared build caches (wh

They are still used in some places. But they have some downsides: Precompiled headers don't play nicely with distributed compilation or shared build caches (which are perhaps the fastest way to build large C++ codebases). So while they can work well for local builds, they exclude the use of (IMO) better build-time optimisations. They also require maintenance over time- if you precompile a bad set of headers it can make your compile times worse.