Please help. CPU hitting 100% even with no plugins.

If i log into the server as an admin, the CPU jumps to about 80%
After a few minutes it's at 100% and I have to quit.
If I'm not connected, it only takes 3-4 people online for it to jump to 100%

Please help, this never happened before 1.3.

Specs:
Intel Quad core
12GB RAM

CraftBucket #531

Plugins normally used (but the issue happens without plugins too):

Essentials
WorldGuard
WorldEdit
GroupManager
iChat
Anti-Grief
LWC
MagicCarpet
[MERGETIME="1300061339"][/MERGETIME]
bump

 

What os and what startup command? Im supposing this is a dedicated?

 

It's probably your startup command.

 

Windows

This is my start.bat file

@echo off
"C:\Program Files\Java\jre7\bin\java.exe" -Xincgc -Xmx4096M -jar "craftbukkit.jar" nogui


I know that my RAM isn't set very high but that is not the issue as that sits at around 3GB with 12-15 people connected and I don't want any more than that.

 

How big is your world file?

 

191MB

 

-Xmx4096M with no server tag? try -server and see if this helps. Just a guess, I am not good with java lol.

 

Might want to double-check your JDK install, maybe reinstall Java.

 

Ok I reinstalled Java and JDK 7
Nothing changed

 

Same issue here.