Here are two screenshots to compare:

FF16: http://i46.tinypic.com/qmxkq8.png

FF17: http://i50.tinypic.com/2qkm9up.png

Nothing has changed in my settings either in Windows or in Firefox. Just simple update from 16.0.2 to 17.0.

Notice how awful the word "mozilla" looks in address bar.

Exactly the same problem. Can't find the option to turn off FF messing with fonts.

I noticed if I turn off the hardware acceleration in tools-options-advanced the fonts goes back to ordinary....but I shouldn't have to turn it off, I have a good graphic card so I want to have this options on

Well disabling HW accel. helps, but only partially. Firefox itself looks good, but fonts on certain sites now looks even more unreadable for me than before.

I have no problems with the fonts within the web sites, it looks as good as it did with FF 16.0.2 but I hope there is a solution because it looks terrible with the Hw enabled

It's actually just one site with custom font that I'm on that looks bad. All other sites look like they should.

I went back to 16.0.2...couldn't stand it :(

Note that on the Windows platform such issues on a web page can also be caused by Firefox placing all members of a font family in one group and selecting a member in that group based on CSS font rules.

You can use this extension to see which fonts are used for text that is selected (right-click context menu: Show fonts in selection).

• fontinfo: https://addons.mozilla.org/firefox/addon/fontinfo/

You can do a font test to see if you can identify corrupted font(s).

• http://browserspy.dk/fonts-flash.php?detail=1

My big issue is that firefox fonts on menu, bookmark toolbar etc looks really bad not on the sites. It looks all compact, blurry and thick. As guniu explained it looks like clear type is enabled...

I have disabled all plugins and extensions even reinstalled graphic drivers but the only thing that helps is to disable the HW acc so I went back to ff 16 for now,

This is a big usability issue for me, since I do a great deal of reading in firefox and hardware acceleration resulting in blurry text makes reading for more than a few minutes induce a very high level of eye strain.

Of course, turning off hardware acceleration is a temporary workaround, but it is far from ideal.

Note that using hardware acceleration means that Firefox uses the GPU instead of the CPU to do some (image) manipulations and that you may not notice any effect in Firefox if you disable hardware acceleration. If the GPU is used then specific operations like scrolling and font rendering that are performed internally by the graphics display driver can take more time (the GPU needs to do more if HA is enabled) and thus the graphics display card can respond less smoothly. There shouldn't be any reason to revert to an older Firefox version because of issues with hardware acceleration that can be fixed by disabling this feature.

See also:

• https://hacks.mozilla.org/2010/09/hardware-acceleration/

But Cor-el, this is an issue that was introduced specifically in this update and did not exist with HW rendering prior, so that isn't really relevant here.

Why you moderators always respond like bots. Just read what we wrote, compare the screenshots I posted. There is something with font rendering in FF 17.0 that has changed since last version. And it looks like crap now.

Maybe source of this problem is hidden in this bug fix - https://bugzilla.mozilla.org/show_bug.cgi?id=777089

I have this problem too. Hate cleartype, so went back to FF 16.02. I think it's major issue that need to be fixed asap. Also noticed that FF safe mode don't have this problem. All this on Radeon 6950 with latest official drivers for Windows 7 SP1 64bit

I too, have this problem, wasn't like it prior to the 17 update, I even went to extreme lengths of removing all add-ons and even reset FF back to default the result is the same, fonts look like cleartype is enabled - like others cleartype looks bad on my system. The fonts are as they should be if starting in safe mode or deselecting hardware acceleration.

For now I've turned off hardware acceleration, but I shouldn't have to.

Huge sense of disappointment when I upgraded to FF17 and this happened. It affected the Win7 PC I use at work but did not affect the XP SP3 PC at home - why would this be? I use "Classic" theme on the work PC and do not have Cleartype (aka. Fuzzytype) enabled.

Hoping someone will post a fix here - have bookmarked this topic for now!

I used the trick of unticking the hardware acceleration option for now - seems to do the trick. Am I fighting a losing battle in my preference for pin-sharp font rendering? We had to update to Office 2010 here recently and I spent time changing back from fonts like "Segoe" to something that didn't blur the edges...  :-(

I reckon people with poor eyesight probably prefer "Cleartype" rendering because it "bulks out" the characters. I try to focus on the unresolvable blur it generates and get a headache! I understand the rationale for "Cleartype" but it's not for me. PC power these days should mean everything is easily and quickly customisable to individual preference, IMO.

I have this problem too guys. I noticed this problem wouldn't happen in Win 7 and for me only on Win 8: could you confirm that?

On about:config, changing gfx.direct2d.disabled to true, resolve the problem.