If we want users to get the best performance, our builds should enable LTO mode (CMake option -DCMAKE_INTEPROCEDURAL_OPTIMIZATION=ON). There are more things we should do to get users the best experience possible, but this is a start.

I've been building on Linux with LTO enabled for a couple of years now and have not had trouble.

Having such configuration enabled would have helped catch QTBUG-133494, for example.