If you are using pure C runtime you really need to consider if you should be using wine at all. There are more and more ways to go native. Currently C runtime ways are faster. Mostly because optimisation has not been done on CreateFile() and the like instead they just wrap to fopen() and so on in glibc. Wrapping has a price. Sorry to say the exact other way to windows. Its one place wine is a mirror image. If you go the C runtime path you will take a hit on windows. If you go the WinAPI path you take a hit on wine.
