Hello,

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thank you.

Didn't help at all. I still see Firefox 25 hang. So do my co-workers. The only common thread between us is we're on OS-X 10.8.5 and running Firefox 25.

Is there any way to get a debug/dump of where the browser is stuck?

It sound suspiciously related to this: http://support.mozilla.org/en-US/questions/977281

So, it sounds like custom font support may be broken. One common thing in the pages that break is they have custom font faces. This is a huge deal. Can someone from Firefox development please look into this.

Did you check the Network tab in the Web Console (Tools > Web Developer; Command+Shift+K) to see if that gives any clues?

• https://developer.mozilla.org/Tools/Web_Console

Do a hard refresh via Command+Shift+R to reload the pages from the server.
You can also try the Profiler.

Does it help if you disable downloadable fonts by temporarily setting the gfx.downloadable_fonts.enabled to false?

Do you have a lot of fonts installed on your computer?

• [/questions/957111] Firefox hangs on Websites (issue with downloadable fonts; having many fonts installed)
• Bug 752394 - eliminate need to enumerate fonts for localized family names and postscript names

I cannot check the console. The hang is a hard hang. The browser becomes completely nonresponsive. Nothing works. I have to force quit (kill -9) to even shut it down.

Reloading the pages from the server does nothing. As noted it is a hard hang. You cannot reload. You cannot do anything at all. You cannot load the profile. The browser is non-responsive.

Yes, if I set gfx.downloadable_fonts.enabled to false, the pages load. It appears to be directly related to the fonts. Furthermore, I do not now if this comes into play but I will note it. One of the font characters in question is loaded into a DIV that has a CSS rotation animation applied. The font character is 'progress ball' type design, using CSS to rotate it. Same technique as used by FontAwesome for its icon font characters and its progress ball. So, perhaps it is related to font rendering in a div actively undergoing a change?

No, I do not have a lot of fonts installed. I have the base set that came with OS-X 10.8.5 + two additional ones I've used for some graphics work.

The total # of fonts installed on my Mac is 276 according to Font Book.

The Firefox process is stuck at 99.9% CPU utilization. If I attach GDB to the process, the current thread stack shows:

1. 0 0x00007fff99687379 in ARGB32blend_color ()
2. 1 0x00007fff99355dd9 in sseCGSColorDeepMaskCopyARGB32 ()
3. 2 0x00007fff9943e803 in CGSColorDeepMaskCopyXRGB8888 ()
4. 3 0x00007fff9930f500 in argb32_mark ()
5. 4 0x00007fff8e19acc3 in ripl_BltGlyph ()
6. 5 0x00007fff8e198577 in ripc_DrawGlyphs ()
7. 6 0x00007fff99563f79 in draw_glyphs ()
8. 7 0x00007fff96e38b88 in CTFontDrawGlyphs ()
9. 8 0x0000000102a8d06c in jsimd_idct_2x2_sse2 ()
10. 9 0x000000ce419e0000 in ?? ()

It's stuck in some sort of color blending loop.

Followup. Any further updates from Firefox support? This is a blocking issue at my company. We are strong Firefox advocates, but this is starting to damage Firefox's reputation here.

There's an issue where using a web font in conjunction with absolute positioning, "synthetic" bolding, and rotating creates an infinite loop in Firefox. I don't know if this applies to your situation or not, but removing the bolding "fixed" the issue for me. The issue is supposed to be fixed for Firefox 26.

Check this issue: https://bugzilla.mozilla.org/show_bug.cgi?id=906704

(fixed example link - c)

That is entirely possible the cause of what is going on. At least it is a hint of where to start looking for a possible workaround. Thanks!

Firefox 26 fixes this issue. I tested the beta today and it works fine on the sites that previously hung. It is definitely due to: https://bugzilla.mozilla.org/show_bug.cgi?id=906704

Hurray for FF fixing that issue.