• Repair System Registry and Files

Find the Dos Prompt Right or Powershell Click and Run as Administrator then : Copy/Paste to Dos Window : DISM /Online /Cleanup-Image /RestoreHealth then hit Enter. Reboot when completed. Note : DISM goes up to Microsoft for new ones.

Is issue still there ? If yes : SAFE MODE

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

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder)
• default toolbar layout is used (file: localstore-safe.rdf)
• Javascript JIT compilers are disabled (prefs: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)
• plugins are not affected
• preferences are not affected

TEST''''is issue still there ?

Please let us know if this solved your issue or if need further assistance.

Thanks for your reply. Sorry, running dism did not solve the issue. In my original post I indicated I had already tried safe mode.

This is a rather unusual problem. As a retired Software Engineer, my instincts tell me this is a Firefox tab issue but I have been wrong before :)!

Hi, yes knew you ran Safe Mode but possibly did not trouble shoot Extensions.

delete a tab ? you mean close a tab. ?

If this is a older system with low ram and old video card as was last updated driverDate: 7-25-2017 then running Win10 and version 57+ would use lots of ram and maybe ram on the video card also which would explain the issue. Below may help the issue, you can test if it does. Go to the 3 Bar Menu then Options --> General --> Performance and untick everything. change the recommended size lower then see how it runs. Note: 1 = No Multiprocessor = slow again. Try 2 Restart Firefox after making these changes please. Note : Hardware Acceleration is for Video Card, Monitor to see if remain off or to turn back on.

Can try these things :

• https://support.mozilla.org/kb/Firefox+is+already+running+but+is+not+responding
• https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster
• https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix
• https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram
• https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

Also 7min fix : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

As mentioned in the original post this is a new Surface Pro with 8gb of memory/256gb disk. This is more than adequate for Windows 10. I already tried most, if not all, of your sound suggestions and it still breaks. I could re-install Windows but I don't have the appetite for that.

I also ran a background program to see what processes might be stealing focus from Firefox and there were none.

As for tabs, I hit the "+" and then "x" for opening/closing the tab. It does not break 100% of the time but it is certainly happens enough to be quite annoying as pages often spawn new tabs. Upon closing/deleting the just opened tab Firefox often freezes.

Again I do not have this issue appearing with any other apps including those I have written myself.

This apparently is not happening to other folks so unless you have some esoteric approach it might be best to drop this.

I do appreciate the prompt responses.

Richard

I suggest that the developers take a hard look at the Tab Opening/Closing logic and assure that there are no race conditions.

In the meantime I have switched to Chrome.

No other app on my machine has this issue thus my suggestion above.

BTW are you developer and if not, do you have access to them?

Richard

hi richard, thanks for reporting this. could you capture and share a performance profile while the hang is in place - this could provide more insights into what's going wrong? thank you

Hi Philipp,

Not sure if I can since Firefox is totally frozen. Also I do not know what performance data you are seeking. If you wish you can PM me and we converse over the phone.

Richard

hi the link in my prior reply explains the procedure. first you'd have to install the gecko profiler addon, click on its toolbar button and hit on record. then try to produce the hang and if you are done and back to a mode that is responsive, click on the profiler icon again and click on capture. this will open the performance profile of the last few seconds that you have captured in a new tab - once it's finished loading, there's a share button on the top right that will produce a link that you could provide here or in a bug report. thank you!

Can't share since Symbolicating call stacks does not finish. Should I paste the json file here?

if the other method doesn't work, then yes - let's try that. you could put the profile online temporarily through send.firefox.com, please just pump up the download limit...

Just finished

https://send.firefox.com/download/9090b8213f/#IQMImUWMPRUQQd4J0KJqMg

thanks, this appears to be the same problem as in https://bugzilla.mozilla.org/show_bug.cgi?id=1446904