Reload on Idle by ClearCode Inc.

Sometimes an webpages increases the memory usage constantly, then you may have to reload the page to release the taken memory. However, it may be annoying that the webpage your are now reading is unexpectedly reloaded.

This addon provides ability to reload tabs automatically only while your PC is idling. For example, if you set the timer "30 minutes", then tabs will be reloaded only while you are away from your desk.