If you run your computer for a long time (several days) with the irqbalance service running, there is a memory leak at around 60 MB/day.
Until the coders get round to fixing it, you can keep things under control by adding the following as an executable file in /etc/cron.daily/:
#!/bin/sh
/sbin/service irqbalance restart
Save it with any suitable name that will help you remember what it's for andf don't forget to make it executable.