Does not use that much for me. I tried 1.5a1 and 1.1.3 and the highest cpu usage was 90% and that was only for a moment. Most of the time during the video the useage was 65-75 percent. I am running under XP SP2 fully patched with 1 gig of RAM.
OK, you're right. But it does hit the 100% mark and it stays that high, for a good while at least. Most of of the time, though, it uses 80 or more of my CPU power when I visit that example site.
Anyway, I love K-Meleon and i'll keep it using it.