Selenium server causes crazy load on box - how to prevent?

I'm running this linux:

Linux host.themepark.com 2.6.32-220.4.1.el6.x86_64 #1 SMP Tue Jan 24 02:13:44 GMT 2012 x86_64 x86_64 x86_64 GNU/Linux

And I run the Selenium stand-alone server on my box with this command:

java -jar /home/l/cron/selenium-server-standalone-2.24.1.jar > /logs/selenium.log 2>&1 &

Here's the problem: as soon as I do that, the server load starts skyrocketing. I even went back and downloaded older versions of the Selenium server, but same results with 2.23.1, 2.23.0, and 2.19.0.

Note that the server load starts going nuts before I issue ANY commands to Selenium or do anything else. All I'm doing is firing up the server, per the command above.

This used to work perfectly on my server without causing massive server load, so something has changed, but I'm not sure what. My server is a managed VPS so I don't know if there is some kind of auto-update script that kicked in or what... but it's a problem.

(Incidentally, even though the server load climbs like crazy, everything still works: after firing up Selenium, my server creates a screen with Xvfb so Firefox will be happy, then a PHP script talks to Selenium to do what it needs to do before shutting everything down. It takes a LONG time, and the load gets all the way up to 8 [!!!] before it is finished, which kills my web server and makes the main site horribly unresponsive... but it does get everything done.)

Any suggestions for what is going on, why it's started doing this and/or, most importantly, how I can make Selenium not kill the server when it starts up... would be GREATLY appreciated!