Here is some information from the dev: http://blog.martin-graesslin.com/blo...ces-explained/
GL2 is what they are trying to use with fglrx for now, and failing. There is no problem when using the Mesa drivers.AFAIK we are recommending GL rather than GL ES / EGL for the fglrx driver. The "GL ES subset of GL2" recommendation was primarily for 3xx-5xx hardware with open source drivers, where the driver exposed GL2 caps in order to run more apps but because the hardware was DX9 rather than GL2 (GL2 needs a bit more in the HW than DX9 but came out after the 3xx-5xx HW was designed) the driver couldn't be completely compliant with GL2 without falling back to software and becoming real slow on many common apps. GL ES 2.0 aligns better with DX9 HW capabilities than GL 2 does. Of course this is all irrelevent for fglrx which starts support with DX10 HW.
Maybe. From what I can tell, the KWin developers are pretty bad at reporting these issues upstream. That said, I would hope that somebody at AMD would care enough about it to make the slight effort of sending 1 email to the kwin mailing list.Am I being naive expecting a bug report that says "we are expecting A from this sequence of OpenGL commands but we are actually seeing B" ?
Or, as i said, just starting KDE 4.7 up, using the graphical options to select the GL2 backend, and watching the driver to see what call is taking so long. I imagine it is probably pretty easy to spot, although I don't know what kind of tools you have to debug the driver.