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.)