This remix contains about 3 to 5 audio snippets or so from the original recordings, like vocals or piano - so all synths, drums & fx are live AU instruments.
Not a single track is frozen and as one can see the CPU meter ranges about just above half at all times. No dreaded bursts at all.
When I open this song in Logic 9 one on my Mac Pro 3,1, which by benchmarks should have about triple the G5's power, it will use about three quarters of CPU. Yes - MORE CPU than the 2005 G5.
Latest Logic X however would not play it at all - it stops immediately after hitting Play.
Unfortunately I have to be compatible with a lot of co-workers and colleagues so I had to switch to an Intel Mac Pro quite a while ago. But whenever I switch on that old machine I am impressed.
It has never let me down and is dead stable. It runs on 10.5.8 with 8GB of RAM with RME HDSP PCI interfaces and a second video card for running 4 displays when doing audio for post.
So if you're into a really powerful machine for virtually no bucks...a G5 is not that bad of an idea, provided you have the nerve to find all your plugs as PPC versions. But a lot of plugin vendors are quite freindly guys and gladly provide you with legacy versions.
And btw. there's Logic 9 too for PPC also...