Okay, when I posted this I was in the middle of doing homework so I didn't...
The ac_users table is created from the website, you must use the install.php file when you load the webapp.
Read more about installing here:...
I've updated my guide with some new information.
Try setting it to:
java -server -Xms1536M -Xmx2G -jar craftbukkit.jar
Bukkit has a scheduler which allows for threading. Call an asynchronous task.
Are you tracking the timings on your plugins? If so can you post the like the 3rd or 4th newest one?
Separate names with a comma.