https://bugs.winehq.org/show_bug.cgi?id=39421
--- Comment #12 from Stefan Dösinger stefan@codeweavers.com --- The way I read your previous findings is that the slowdown isn't caused by sysmem -> video memory image transfers, but by compositing the rendered image into the quartz display output. This is also confirmed by your winemac.drv based hack working. If you skip glFlush calls in winemac.drv you're in no way changing how wined3d transfers the image to OpenGL.
There are plenty of improvements in the way wined3d handles framebuffer maps that can be done that help some games (and potentially hurt others), but I doubt this is the real issue here.
You can try to use Quartz Debug (part of the graphics developer utilities) to force beam sync off and see if that improves rendering speed.