BTW, This is how I describe ridiculously large.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode

Try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

See also:

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I started in safe mode without hardware acceleration with the default theme, and the problem was still there

Any luck with disabling Tabs on Top?

Current Firefox versions only show the "Tabs on Top" menu entry in the "View > Toolbars" menu and in context menus if the tabs aren't in the default position on top.

If the tabs are on top and the menu entry isn't available and you want to move the tabs below the navigation toolbar then you need to flip the browser.tabs.onTop pref to false on the about:config page.

• http://kb.mozillazine.org/about:config

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

You can also try to reset Firefox:

• https://support.mozilla.org/kb/Basic+Troubleshooting

Yeah I pretty much tried that already.

I temporarily moved all the files from \%appdata%\Roaming\Whatever somewhere else and started up Firefox. From there I proceeded to toggle the tabs on top.

Could this be a Windows 8 problem? If it's not my User Data then it must be a larger issue, like my hardware, OS, or the program itself.

Creating a new profile in Windows fixed the problem. Even after merging most of my old AppData.

PS If you delete a profile in Windows from a different profile and select "Keep Files" it will still toss your downloads. (80GBs of ouch)

I created a new profile and it didn't work out! albeit it is not huge but it's bigger than normal.

Also having this problem, tried disabling hardware acceleration, tabs-on-top, new profile, safe mode and the rest. No dice - running Windows 8 x64 classic theme if that helps.

See:

• [/questions/941577] Firefox Tab Height under Windows 8 is double sized