They're too many mobs spawning, When I do /butcher they're over 800 after 1 second, then I do it again and they're 880. FIXED: I went into bukkit.yml and edited the spawning.
Try this http://dev.bukkit.org/server-mods/mobmanager/ Also, inside of your bukkit.yml, you can reduce how often mobs are spawned. ticks-per: animal-spawns: 400 monster-spawns: 1 Those are default values, I use about 10 for monster-spawns on my server
Its generally a good idea to leave your question, in case someone else has a similar problem later on
I think people who do that kind of egotistical behaviour should be warned or banned from forums. It's almost as annoying as "hey guys, never mind, I found the solution, and I will never tell what it was".