This explains in a good way what I was talking about on my other post about
vista being far slower than XP in the Classic theme.
Problem #3: Eliminating GDI hardware acceleration.
Windows Vista has a new desktop window manager (the DWM) which provides 3D
acceleration to the desktop. This is very nice for future applications. But
in the process of doing this, Microsoft eliminated 2D acceleration entirely.
For the past decade, Windows programs have used GDI for their on-screen
drawing. And video card manufacturers provided hardware acceleration for
this. But now in Vista, this acceleration is gone and the result has been a
noticeably slower desktop -- particularly with programs that make heavy use
of GDI drawing routines.
It's a little flabbergasting to developers who were told to use GDI and GDI+
for years to suddenly have their apps no longer performing as well as they
did on Windows XP. I am not even sure why Microsoft did this.
Solution: Bring back GDI acceleration
reference towards the middle of the page
http://www.vistablogging.com/index.aspx?p=2