Thunderbird uses Direct2D hardware acceleration (enabled in version 5, disabled in version 9, and then re-enabled in version 31) to improve display performance. However, it can make it much worse if you have a low end graphics system. It can be disabled by setting gfx.direct2d.disabled true and layers.acceleration.disabled true using the config editor. You can verify this by looking at the "GPU Accelerated Windows" line in the graphics section near the bottom of the screen for help -> troubleshooting information. It is set to 0 if hardware acceleration is off. If its on you should see something like 1/1 Direct3D 10.

Thunderbird is running very very slow with hotmail accounts. I don't have add-ins and also tried the fix below. Thunderbird uses Direct2D hardware acceleration (enabled in version 5, disabled in version 9, and then re-enabled in version 31) to improve display performance. However, it can make it much worse if you have a low end graphics system. It can be disabled by setting gfx.direct2d.disabled true and layers.acceleration.disabled true using the config editor. You can verify this by looking at the "GPU Accelerated Windows" line in the graphics section near the bottom of the screen for help -> troubleshooting information. It is set to 0 if hardware acceleration is off. If its on you should see something like 1/1 Direct3D 10. Running Windows 8.1 Pro