Server Lag-timeout with 1 user online

i've been having some issues with lag recently, where the server will randomly timeout everyone, almost in waves. I'm running a 3GB RAM vps (i know... vps==bad), but i didn't think it was THAT bad, where it couldn't run with even 1 person online.
I knew it was getting bad when i would restart the server, and it would be only me online, and the server would timeout. My RAM usage (as viewed through MCMyAdmin), shows very little ram usage. The VPS view of the actual server, shows that the server is using all of the memory it has been allocated.

Everthing is up to date as of 8/29/11, and my plugin list is below:

What's even worse, i was running this same basic setup about 2 months ago, with 30-40 active players at a time, and i didn't get any timeouts.



My theory::
*A plugin is causing a memory leak, slowly causing the MC sever to timeout (i've noticed that even after i shut down the mc server/kill the process via ctrl+c, even after 10 minutes, the server administration panel for the vps, shows that the vps is still using nearly 100% of the ram that i allocated (basically, the ram isn't being released)
*At first, I thought that it had something to do with multiverse, but after seeing noone else had any major problems with multi-world stuff, i took that out of my ideas.


Anyone have any ideas of how to troubleshoot this? I've been avoiding the whole thing where you take off all the plugins, and try from scratch, because the problem isn't consistent. Some times it lags, and some times it doesn't... as far as i can tell, the init for the lag isn't visible.

 

I know that you don't want to get rid of all of your plugins and put them on 1 by 1, but maybe you could do a smaller version of that? Take out the following: Multiverse (all parts), RawcriticsOreObfuscationPlugin, CraftBook (all parts), and noCheat. If that fixes your problem, put NoCheat back on, then all parts of Multiverse, then all parts of CraftBook, then ROOP.