There are a few things to try in the threads below...maybe start by updating your Java
If none of those help, use the forum search to look for high CPU, too much CPU or 100% CPU - you'll be able to go through older threads.
http://www.gnutellaforums.com/showth...ght=100%25+CPU http://www.gnutellaforums.com/showth...ght=100%25+CPU http://www.gnutellaforums.com/showth...ght=100%25+CPU