Originally Posted by AaronP
PowerMizer will raise the GPU clocks to maximum performance levels when an OpenGL application is started, but will reduce the performance level again to conserve battery power and reduce heat output if the GPU is being under-utilized. Compiz spends long periods of time idle, so the GPU ends up in its lowest power state. It may be possible to add an option to force the GPU into maximum performance mode all the time, but there will be a tradeoff with increased power usage. By continuously running nvidia-settings, you're forcing the GPU to stay in maximum performance mode all the time.
Thank you for giving us an answer. However, it seems weird to me that some people are facing this issue and some others not, on the exact same device.
I made a script I run at startup to force that -full speed mode all the time- as described above.
I still get lags while using Compiz, and I was getting better performances with my 2 years old ATI X700, which seems...weird.
Anyways, you learn by making mistakes, and now I know I will never buy a cheap Nvidia card again.
If some driver update or any kind of hack can make compiz smooth with that card, please keep us posted.