Those benchmark numbers are slightly misleading, as they are a comparison of Wine+ntsync against Wine+nothing. There has been a somewhat fast "fsync" library built around Linux's futex and the gains over Wine+fsync are modest (just a few % in most cases).

That said, Wine+ntsync is still a win, just not a 8x improvement like the Dirt 3 benchmark suggests.

(And it case it's not clear, ntsync is https://docs.kernel.org/userspace-api/ntsync.html, which is a driver for Linux that offers syncronization primitives (mutex, semaphore, events) that more closely match the semantics of the Windows primitives. It's easier to do a direct implementation in Wine to support code compiled for Windows that expects to be talking to an NT kernel.)