@supasso: even throttled down, current cards far exceed the capabilities of older 2D cards; the problem is that, if an operation is badly optimized, it can slow down even the most powerful system to a crawl, by requiring thousands of CPU cycles and as many sleep() cycles, to perform something that, on said older hardware, would take a few cycles at best.
One good area to look at here, is the Linux world. Why is it relevant?
- dixit an AMD engineer, 90% of the Linux driver code is common with Windows'. That includes 2D, video and OpenGL.
- there are two (well three, but this is not really relevant here) Ati card drivers for R600/700 cards: one (proprietary, very close to Windows) from AMD, one (FOSS, based on AMD documents and reverse engineering) from the Xorg development team.
Benchmarking those in 2D (say, with X's own benches and GNOME's) shows that the
FOSS driver is around 4 times (and in some cases, 100x) faster than AMD's driver on purely 2D operations - showing that, indeed, AMD's driver needs a kick in the arse to push windows around.
Please note that Xorg does also provide purely 2D (EXA+Render) and 2.5D (EXA+Composite) modes. enabling Composite on AMD's driver causes it to slow down across the range, while it actually improves things on the Free driver when used with a compositing ('like Aero', although it actually came out before) window manager - and a GPU that is at least level with a Radeon 9500.
Please note that the very same thing happens with Nvidia hardware, eventhough Nvidia seems to have done a slightly better job at supporting 2.5D (the difference between Nouveau and the Nvidia blob is less apparent).