Flash on any type of CPU is generally very heavy in usage. More so for the older CPUs. Specifically speaking, Power PC G3s and G4s.
If you’ve ever had the pleasure of using a machine with one of these chips in recent years with Flash version 9 installed, it’s not a pretty site. Flash is heavily CPU intensive and will not hesitate to max out your CPU on sites such as Youtube. Not only that, it’s also very jittery at first. It needs to buffer any flash content before you view it. For example, if you go to watch a Youtube video, once the page loads you’ll need to instantly pause the video and wait for it to load about halfway through (sometimes all the way), then hit play. Otherwise the video will be roughly 2-5 frames-per-second until the video is fully loaded.
Not a pretty site, but alas there’s hope! You can download the release candidate of Flash version 10. Version 10 will not decrease the amount of CPU used by much (Youtube still maxes out my CPU when viewing videos on my iBook G4), however you will notice a difference as version 10 adds graphics acceleration. What this does is offloads a bit of flash onto your GPU versus your CPU. No need to buffer flash!
So download it if you haven’t and enjoy.

