Hello,
You can blacklist zones with group of mobs.
In general settings you can put lower value at "Max units near target".
You can also try this plugin: https://wrobot.eu/files/file/1124-avoidit/
When you use XML fightclass, to lower CPU usage you can put lower value in fightclass option "Frames Per Second" (you can try 10 or less).
In the last update I tried to improve the CPU usage.
Try to disable your fightclass/plugins and reactive one by one to check if problem is caused by one of this file.
In TBC with simple Fightclass (without plugin): (up to 2/3% of UC in fight)
Follow this guide https://wrobot.eu/forums/topic/1381-repairinstall-wrobot/#comment-966 you need to run WRobot in window mode, and try to use "Automaton" to start