I'm glad I found this post. I'm experiencing the same problem on three different machines running Ubuntu 11.10:
1. a Sony Vaio VPC F11S1E (GeForce GT330M),
2. a generic AMD A8 Fusion box with a GeForce GTX460, and
3. an iMac (2009 model) with a GeForce 9400.
The symptoms are: from start, things are buttery smooth. Then, if I open Firefox things are still buttery smooth for a short time, then everything becomes laggy and jerky.
All three machines were running 11.04 and did not experience this problem.
I'm glad I found this post. I'm experiencing the same problem on three different machines running Ubuntu 11.10:
1. a Sony Vaio VPC F11S1E (GeForce GT330M),
2. a generic AMD A8 Fusion box with a GeForce GTX460, and
3. an iMac (2009 model) with a GeForce 9400.
The symptoms are: from start, things are buttery smooth. Then, if I open Firefox things are still buttery smooth for a short time, then everything becomes laggy and jerky.
All three machines were running 11.04 and did not experience this problem.
Compiz performance deteriorates with usage.