Sywindt
Ryzom has, to my knowledge. always taken 100% of CPU if allowed, but scales back if other activity is going on. The last patch was months ago so there has been no change to the client.
Perhaps some local thing has changed? New software installed that is running in the background or something similar?
I thought the same so i re-installed windows. It was the same. Than i deleted the game and re-downloaded it, installed it, re-patched it, and now i can Multibox again with no problems.
Maybe the files got too fragmented? Can it be?