never mind figured out it was one of my extensions messing with my theme

Happened to me a few times too.Usually the extensions mess up the home screen default add-ons.

Sometimes, after switching from one tab to another one, Firefox looks like being frozen/hanging. But after switching to another _application_ and then switching back to Firefox window, it works fine, and tab is actually already switched to the one that I intended to switch before Firefox has been frozen.

Note that this does not occur always, just sometimes, so it's hard to determine what exact 33.x build has introduced the bug.

FWIW, I use Windows 7 Home Premium as OS.

Expected results:

Firefox should repaint its window correctly when switching tabs — without looking hanging — i.e. Firefox should work just as Firefox 32 and earlier versions before Firefox 33.

When you switch to the light or dark theme on Windows 10, supported apps also switch their mode to align with the color with the rest of the environment.

Although Firefox isn’t an app available from the Microsoft Store, it’s been updated to automatically follow the color theme you set on Windows 10. However, if you want Firefox to use a specific theme color no matter the mode you use in the operating system, you can quickly accomplish this by changing the browser settings.

In this guide, you’ll learn the steps to set a permanent default color theme on Firefox to prevent the browser from changing colors when you switch to light or dark mode on Windows 10.

1 - Open Firefox. 2 - Click the menu (hamburger) button on the top-right corner. 3 - Click the Customize option. 4 - Select the theme (Light or Dark) that you want to use.

Once you’ve completed the steps, Firefox will remember your settings, and it won’t change it the next time you change your system color theme.

If you want to revert the changes, you can use the same instructions outlined above, but on step No. 4, make sure to select the Default option.