Two suggestions Rated 4 out of 5 stars
Great add-on. I have 3 suggestions:
1. Please add a toolbar button (not by default, but make it please available)
2. I think it would be a great idea to make a few presets. Like "making firefox have a faster startup" or "surfing faster with firefox" or "let firefox responds faster". Also giving a short description for a preset, incl. the down sides of a particular preset.
3. See if it's possible to include a button in the main preferences window, like tab-mix-plus does. There is already a advanced-tab.