Using llvmpipe to run a composited window manager = slow GUI.
Have you actually tried using llvmpipe? Any additional stress on the CPU hits the performance hard. It's easy to try it out by yourself. Run you fav game in llvmpipe, try launching a couple of CPU intensive tasks - boom performance drops to the floor. Do the same test on a normal setup - the performance impact is negligible. Now imagine that the game instead is kwin or compiz....
Keep in mind, sarcasm, irony and snarky remarks doesn't translate well in text. There might be a language barrier here too, english isn't my first language. It would be a lot easier if you just said what you wanted to say instead of replying by posting comics.
Heh, at this point it becomes quite obvious that you haven't tried this out yourself.
The performance penalty is several orders of magnitude greater when you're doing the rendering on the CPU rather than offloading it to the GPU.
I'll say it again just to be sure, the time spent processing data (on the CPU) before it gets sent off to the GPU is negligible compared to the time spent rendering it on the CPU.
Don't take my word for it, run a few tests yourself, I don't think kwin/compiz/g-s is usuable with llvmpipe yet, but any game or demo should suffice to prove my point.
I guess this was a misunderstanding when it comes to theory versus practice. Yes - in theory you get a slowdown in both cases - but there's a clear difference between a microseconds delay and "oh my god why is my mouse cursor taking three seconds to move from one side of the screen to the other".
I tested Extreme Tux Racer (same specs as above) and both were nearly playable at 10-15 fps depending on resolution. That's strange, but it seems llvmpipe's speed depends only on resolution, and not on the number of objects/detail/filtering. Anyone can explain this?
I get 13 fps on Extreme Tux Racer with highest settings at 800x600 and 7 fps at 1280x800.
I use kde 4.5. Its compositor do work only with proprietary drivers because it makes use of opengl2 extensions still not supported by open drivers. So I simply do not use it at all and I don't know if it works with LLVMpipe. Anyway kwin 4.4 should run quite well even with llvmpipe.
KDE 4.5 works fine with r600c from Mesa. Including blur.
It did take some twiddling, though, and I had to remove some blacklist entries by hand. It was probably some effect I was using before that barfed up. Starting with a clean KWin setup (deleting kwinrc) and configuring from there fixed it.