Ok so just like many other people, I also suffer from high CPU and RAM when using iBot and Tibia, especially with MC's.
Eventually I found the source of the problem - HUD!
1. Load your script
2. DELETE everything from HUD.
3. Set HUD OFF!
Now you will bot with much less CPU and better FPS.
Yes I know, the game won't be like with HUD, but let's wait till it's fixed
I hope I helped you guys, because this is better than all stupid tips like "Clear Registry" and all these..