Chrome, Firefox, and the Windows kernel all ship PGO-optimized release builds because letting the compiler see real branch frequencies from actual usage, rather than guessing, routinely buys 10-15% wall-clock improvement for free. AutoFDO, the sampling-based variant Google popularized to apply PGO to already-deployed production binaries without a special instrumented build, is a direct descendant of the -fprofile-generate/-fprofile-use workflow you run here.