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.)
Ironically, SQL Server AFAIK in order to run on Linux uses what basically amounts to a Microsoft reimplementation of Wine. Which always makes me wonder if they'll ever get rid of Windows altogether someday in favour of using Linux + a Win32 shim. I think there are still somewhat strong incentives nowadays to keep NT around, but I wouldn't be that surprised it this happened sometime down the line.
AFAIK it's more like a reimplementation of NT APIs in userspace - aka basically Wine with extra steps, or Linux UM. There was a slide deck going around about Project Drawbridge, here: https://threedots.ovh/slides/Drawbridge.pdf
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.)