A while ago, a friend of mine showed me the Load Time Analyzer for Firefox. It’s a pretty cool tool that can analyze all of the different HTTP requests that make up a page load. Then it can display a simple graph showing how long all of the requests took. It could be very useful for trying to identify requests that are slow to load.
I recently had a reason to use the plugin, so I turned it on and found what I needed to. I removed the toolbar for it when I was done with it. But the past couple days, my browser has gotten painfully slow after being open for a couple hours.  It was using a ton of memory, and just loading a simple page, or opening a new tab would sometimes take ten seconds.
Turns out that the Load Time Analyzer was still running, even though the toolbar wasn’t being displayed. It was keeping track of everything page I visited, which is why it was using so much memory and running so slowly.  To actually disable it, you have to go into your ‘Addons’ menu, and actually disable it.  That, of course, requires a browser restart, which is kindof annoying.
It would be nice if future versions had an option to disable it without a browser restart. For now, make sure to enable it only while you need to use it.