Closing/hiding as much windows as possible usually do the trick. Since CRC has lots of members if you switch the social window (F11) tab to the Guild one you add a considerable amount of load. I usually keep the player tab open (P) to have a "quick and dirty" glance about nearby and hurt players.
While idling or afking minimizing client drops CPU load a lot. Sometimes even changing active desktop or console on *nix OS may help too.