What porting you talking about exactly? Packaging existing binaries? Compiling source code making it more compatible with Wine?

In my experience as game developer and porting C++ code tells such difference usually mean there are something really wrong with syncronization primitives. So 99.99% of the time code does nothing just waiting for something to unlock.

Yep, I’ve seen issues like this before. Run it in a profiler and you’ll see it only doing useful work like 5% of the time.