Version: unspecified (using KDE 4.6.2) OS: FreeBSD I have NVidia GeForce 9400GT with native drivers on FreeBSD on intel quad core cou 9200 @ 2.67GHz. When window effects are enabled, switching tabs is very slow causing for example mplayer to pause briefly. Changing windows also sometimes causing hangups, but in konsole it is particularly pronounced. Reproducible: Didn't try
Do you use flip switch effect when switching windows by Alt+Tab ? IIRC, that effect is problematic between 4.6.0 and 4.6.2 .