If your Thunderbird has a lot of emails, you’ll notice that it slows down drastically and even basic navigation becomes a problem. There are a couple of tips to help speed things up:
Navigate to “Preferences” and in the “Find in Preferences” search box, search for “Config Editor” and set the following options:
layers.acceleration.disabled = true
gfx.direct2d.disabled = false
If you’re using Windows, you can disable “AeroGlass”, which will improve the speed.
Finally, if you’re not using search functionality, you can disable folder indexing:
Go To Preferences → Advanced → General tab and disable the Global search
Now, restart your computer and open Thunderbird for an improved experience 🙂