So just over 50% CPU usage is way too high?
Just tested Flash out in Safari vs Chrome... CPU usage in Chrome is only slightly higher than in Safari. Obviously, different computers and situations behave differently.
Check out the CPU cycles being taken up by Flash plugin for Chrome alone. Within seconds my computer starts sounding like a jet engine.
Safari (or Firefox) never get that high. Yes, it might be just over 50% (usually higher than that...like i said mediocre quality 720p) but why is Chrome special. The other browsers rarely get that high.
Then again as you say its all individual, for my use though, Safari>Chrome>Firefox.