I just wonder about one thing: are all those problems really a PowerMizer issue? In my case (8800M GTX) performance is cut by half both with and without drivers loaded. It probably means that, to prevent emission of excessive heat in absence of PowerMizer, level 1 is the default and it needs to be somehow forced in order to go higher, what PowerMizer is responsible for. In such case, wouldn't getting rid of it have the same effect as unloading the drivers? This is why I think it needs to be fixed, not disabled.
There already seems to be a way to turn the thing off with xorg.conf and, aside from that level 1 barrier (not necessarily directly caused by PowerMizer), it works for me, so by voting 'yes' I mean a possibility to control it without restarting X, preferably that way:
Originally Posted by damentz
performance (essentially off, in your case kernelOfTruth)
powersave (lowest clock/memory/voltage, regardless of usage)
ondemand (raise clock/memory/voltage to factory defaults on usage and reduce to lowest under no demand)