I've got an HP EliteBook 8530p. I have run prior versions of Ubuntu on this machine, but I've recently formatted and put 11.04 on it. No matter what I try, the CPU throttling goes in reverse - when my CPU usage is high, the frequency is actually REDUCED. This is very weird, and I can't figure out what's going on. Any ideas?
It may be related to this issue & fix posted on the Ubuntu forums:
"No cpu frequency scaling possible"
"I have an IBM Thinkpad T40p with a Pentium M 755 2.0 GHz CPU. After upgrading to Ubuntu 11.04 from 10.10 the CPU is incorrectly underclocked to 598 MHz and cannot be adjusted, manually or automatically. When I boot off the old 10.10 live CD, CPU scaling and all the governors work again perfectly."
I'd advise you to get a processor temperature monitoring program running and see what that says when you are using the machine. It is possible that the CPU is being throttled back due to high temperature rather than high workload.
If your CPU is getting hot then you'll need to make sure that all air inlets are clear and free from dust. You can also get "cooling pads" for laptops to help keep them cool.
Check out PSensor (and this handy guide) to get some idea of your CPU temperature, if you can't find something via the Software Centre.