These days our StretchRect and some other calls are accelerated by XRender. If you have good display drivers (e.g. Nvidia, and perhaps in case of ATI catalyst 10.6 and perhaps recent Intel as well) then XRender is hardware accelerated and thus StretchRect as well. Note the frequency of calls doesn't say anything about performance. If something is slow you would have to profile it to find the real cause. If the app is doing a lot of drawing to DIBs then X11 might be the issue (on Windows DIBs are rendered to in software using a DIB engine but in Wine we cheat and offload everything to X11 which can cause performance issues in some cases).
