I wouldn't put it that dramatically. I did 96k/24bit recording on a quad core G5 a while back and would run nearly 30 real time effects - reverbs, compressors/limiters/gates, the usual. I can't recall the CPU going above 50% capacity.
That was an 9 year old machine, and I have to say peeking back in on the digital audio industry, not a lot has changed. Most of the prosumer gear is still 96k/24bit while the pro studios go for 196kHz, but that was around back in 2005 as well. The one thing that has changed is that desktop and mobile CPUs have gotten a ton more powerful with more and more cores.
I suppose you mean 192KHz.
Times have changed since you worked with your G5. Many projects now are 60+ tracks and plug-in count is sometimes 200+. Also many plug-developers are now into analog modeling plug-ins that are real CPU hogs. Try instantiating 80 Slate Digital VCCs followed by 80 VTMs, add EQ, compression, convolution reverbs and an I7 iMac will crumble with the CPU demand.