I just recently reinstalled Kubuntu on this laptop, and since its a fairly stock install at the moment, I suspect that this is a general (K)ubuntu bug, and not something related to me screwing around with my system. In addition, since I switched to using Kubuntu full time, this is the first time I've seen transparency and other desktop effects, and system performance has improved dramatically. While I can't say for certian, I suspect that my system was also affected on its previous install. Part of the issue may be related to what packages are seeded per flavour, so this bug may only affect those who installed Kubuntu over say Xubuntu or Ubuntu; without more information, its impossible to say.
This is where you can help; if you are running any flavor of Ubuntu with an Intel based video card, you might be affected by this too.
Here's how to check; open a terminal, and type:
mcasadevall@daybreak:/var/log$ cat /var/log/Xorg.0.log
then find the section where the glx module is loaded. It looks something like this:
[236901.570] (II) LoadModule: "glx"
[236901.571] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so
[236901.578] (II) Module glx: vendor="X.Org Foundation"
[236901.578] compiled for 1.10.4, module version = 1.0.0
[236901.578] ABI class: X.Org Server Extension, version 5.0
(this is on a machine where the Intel acceleration is properly working).
If it says 'ATi' or 'NVIDIA', you've run into the same issue I have. So dear readers, I ask that if you've had any issue with graphic performance, gaming, or simple UI lag and have an Intel video card, please post a comment with you video card, what flavor of Ubuntu you have installed, and the glx section of Xorg.0.log. If I get a few reports that confirm this, I'll file a proper bug in Launchpad, and then work to get this fixed.