[Zope] asyncore.poll

Recently my development site has started getting _really_ slow a few times a day. Stopping and restarting Zope makes it quick again. When it's in this slow state, I open a python interpreter and run Zope.debug() to get profile information. This profile shows a huge amount of time being spent in asyncore.poll() (like 25 seconds on a 25.2 second request). I'm running ZEO and Zope 2.3.1b1 on Linux. Any ideas? Thanks, -Randy