The problem with XP is, it was not optimized for multi-core processors, because they weren't around back then. Vista and W7, on the other hand, are built specifically with multi-core in mind and perform better than XP on such systems. It would probably have been more troublesome to dig out the old XP source code and re-write it to support multi-core better. At least that's my hypothesis.
Just Cause 2
- Thread starter SharkClub
- Start date
That's what the service packs are for. XP is still used widely these days. If I look at the forum statistics of another community I hang out, 38% of the users are using Windows XP, and other 24% Windows 7. While it may be one of the reasons newer OSes perform better because they are written to support multi-core systems better, it doesn't have much to do with applications that want to use them.
The main problem is that the developers just probably aren't interested in porting DirectX 10/11 specific code into DirectX 9, mainly because of the integrated pixel/vertex shaders.
There was a project for adding DirectX 10 support to WindowsXP(Alky Project), but I think they kind of gave up, but all the source code was released. I haven't checked if they progressed though.