Are you rocking an Intel 945GM chipset with the integrated Intel 943/940GML Express Integrated Graphics Controller (rev 03)? If so, this little tweak has helped 3 of us thus far in #kubuntu-devel with KDE 4 and compositing effects.
Step 1: xorg.conf editing
Section "Device" Identifier "Intel Corporation Mobile Integrated Graphics Controller" Driver "i810" BusID "PCI:0:2:0" Option "AccelMethod" "xaa" EndSection
This is what our device section for the graphics card looks like. We added the “AccelMethod” “xaa” option.
Step 2: ~/.bashrc
Added that line to our ~/.bashrc file.
We then restarted X with a swift Ctrl+Alt+Backspace and then tested this setup with glxgears and we all received an average FPS of well over 1000. Prior to this, my highest FPS was a low 900. After these little tweaks, composite never worked so smoothly in KDE 4 in the past.
Does this tweak work for others using say Compiz? Are there some more Intel tweaks that you know of that help out as well? If so, add them to the comment and attempt to explain exactly what they do. Thanks!