1. Enter about:config in the address bar and click through the warning
2. Enter gfx.font in the 'Filter' box
3. Double-click on gfx.font_rendering.directwrite.enabled to set it to true
4. Below this, right click and select New > Integer to add a pref setting
5. Enter mozilla.widget.render-mode for the preference name, 6 for the value
Meanwhile, tab sets (along with app tabs) should help you manage unruly numbers of tabs. It allows you to create groups of tabs that share a similar purpose, such as research on an item you're looking to buy or communication sites like Twitter, Facebook and so on. If you're unfamiliar with the feature, you can watch a video demo after the break.