I have to take issue with that "perception of slowdown" comment even if this is a bit pointless discussing about legacy stuff - it does however suggest there's room to improve on this area (atleast by cpu+gpu chips from intel/amd).
I already posted links to benchmark tool and results which fly against your comment and my own tests in past (when I had AGP card with a dedicated chip for GDI acceleration). Those dedicated 2d chips aren't shipping with Nvidia since I think it was 7xxx or 6xxx series. I don't have a reference to this right now but years ago I read reviews which made a point of this. The results in the benchmark, along with my own experiences of windowed stuff slowing down noticeably when moving to 8800 support this.
So when it comes to pushing 2D stuff to screen in windowed mode as fast as possible, XP, in best case can be 10 times faster (on legacy gdi apps) than Windows 8 in best case (since it no longer has support for XPDM based on the Build compat-session I saw here). In windows Vista/7 there may be way to install XPDM driver, but I can say that so far I haven't been able to install Nvidia XP-64 driver on 64 bit Windows 7. Maybe the 32 bit one would work (for win 7 32).