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

Profile Backup and Restore

• http://kb.mozillazine.org/Profile_backup
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Maybe it is possible caudes by duplicated files after the updating. You can go to local disk to delete juck files. Also you can clear out all cookies and browsing history out from your Main Internet Browser to upgrade Online Experience

Usually slowness after one upgrade requires disabling hardware acceleration, or a possible new regression (hopefully not).

You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

Then perform these steps:

• Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
• In the Firefox options window click the Advanced tab, then select "General".
• In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
• Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Thanks, it appears to be working a bit better now. I'm not sure what fixed it, though, but thanks for the responses.

hardware acceleration was already unchecked on mine - it does this after every single update, even in safemode with everything disabled.

This always seems to happen with updates. They fix a bunch of bugs, but create new ones, or don't fix old persisting ones. I was under the impression that Firefox speeds up with every update, but it would seem to be the opposite. I am perturbed that users have to jump through hoops to find workarounds. eg. Things were working just fine before, now that it isn't after the new update, we have to delete old user profiles, dig through subfolders to find duplicate files created to delete, and restart from scratch. Which can take hours of your time. All because Firefox messed things up. If Firefox broke it, they should fix it. Not us, we don't get paid to do their job. I'm always for "if it's not broke, don't break it, so you don't have to fix it." Also what's the point of having a "hardware acceleration" feature, if it doesn't work?

Still the same with v25.

v25 is actually working much better for me now. I still notice after a while of Firefox being open and used, it does still tend to slow down. But much less than v24. ie. scrolling stutters, but no longer hangs for a few seconds. Deleting history, and cache doesn't help. But restarting Firefox does. Until it starts happening again. Better than nothing. Better than using Chrome. And definitely better than the previous version.

Version 26 seems to have solved this problem.