Cpu Usage Vs Audio Quality, audio degradation in native systems Options

[bjkiwi]

has anyone noticed the sonic integrity of their audio tracks degrade as the cpu is made 2 work harder? Obviously if the cpu max's out it hits a brick wall and dies but is there a difference between, say, only using 25% of your cpu (maybe a couple of compressors) and 75-80% (bringing in those reverbs!)? Like, the audio quality is inversely proportional to the cpu usage.
I've often wondered whether there's a trade off in audio quality (reading and processing the audio off the hard drive) to get more plug-in's going.
Sometimes I think I've heard the sound 'soften' or lose it's edge or transparency and depth as the cpu meter winds up.
I'm interested if anyone has pondered the same question, noticed any difference, or knows the answer.
I'm running Cubase 5.0r2 on a G3 400 with waves plug-ins. (I know it's old and slow but I've got it humming quite nice...a bit like old motorbikes, they just need some attention and understanding, but I digress.)
thanks..Bjkiwi