Autenil is currently working on memory issues, specifically the memory boundaries.
Part of the problem with Vista and memory usage is in the way that Microsoft supports DirectX 9 applications. Vista actually creates a second copy of every texture in memory. This is the root of many of the memory issues on Vista and we are looking into ways of fixing it.
In regards to slow framerates on Windows XP, if you are not experiencing screen freezes every 10-15 seconds, then you have a different problem than the one reported with 8800 series cards on Vista. When I say that I haven't heard any reports of 'this problem' on XP, I'm referring to the screen freezes.
We have been able to reproduce these screen freezes on a Vista machine and someone (not me) is looking into it now. When I hear something, I will let you know.
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