It's probably a Mobile Substrate extension (or a combination of them). Some Mobile Substrate extensions do like to chew up lots of resources.
redsn0w and Corona were updated not too long ago to address a problem with "launchctl." (PwnageTool was not updated, though.) Just re-jailbreak with the new redsn0w (be sure to uncheck "Install Cydia"), or install the new version of Corona to get the fix. (It doesn't matter which path you take; you'll have the same thing in the end.)
redsn0w and Corona were updated not too long ago to address a problem with "launchctl." (PwnageTool was not updated, though.) Just re-jailbreak with the new redsn0w (be sure to uncheck "Install Cydia"), or install the new version of Corona to get the fix. (It doesn't matter which path you take; you'll have the same thing in the end.)