Fix Firefox 4 Fade, Blur, Bold (Bad and Ugly) Font Rendering
Firefox 4 has added GPU hardware acceleration support for graphics rendering, which intends to make browsing of Internet faster by switching to let display adapter to process visual output for performance improvement, which is what the graphics card intended for. Firefox 4 makes use of Direct2D (D2D) and DirectWrite (DW) text and graphics APIs to provide hardware-accelerated rendering of 2-D geometry, bitmaps, and text.

Bold font display on Firefox 4 with hardware acceleration enabled

Incorrect font display on Firefox 4 with hardware acceleration disabled
However, the hardware acceleration feature of Firefox 4 does come with a major downsize, which is that Firefox renders fonts not so smoothly leading to faded, aliased, hazy, porous, fuzzy, blurry, and bad fonts in text display which may be unreadable, and definitely messy and ugly. Worse, some text appears to be fatter, bigger, bolder, wider and larger instead, causing the row width to be longer, spacing and layout out, or the text looks squeezed or squished together. The issue happens in both chrome (out of content area) and content area of Firefox.

Blur font display on Firefox 4 with hardware acceleration enabled

Normal standard font display on Firefox 4 with hardware acceleration disabled
If you’re having the blurry and bad font rendering issue in Firefox 4, here’s a workaround to fix the font issue in FF4, by turning off the hardware acceleration support in the Firefox’s options.
- Click on Firefox menu and go to Options -> Advanced section -> General tab.
- Unselect and untick the check box for Use hardware acceleration when available.

- Restart Firefox.
Alternatively, if you prefer not to completely disable the hardware acceleration support of Firefox, it’s possible to partly disable hardware acceleration by Direct2D and DirectWrite by changing advanced settings of the Firefox:
- In the address bar, type in about:config and hit Enter.
If promoted with a “This might void your warranty!” warning, click on I’ll be careful, I promise! button.
- Search for gfx.direct2d.disabled preference name.
- Double click on the preference to set it to True.

- Search for gfx.font_rendering.directwrite.enabled preference name.
- Double click on the preference to set it to False.
Note: By default the setting should be “False”. It’s not necessary to set it to “True” in order for DirectWrite to work, as where Direct2D (hardware acceleration) is turned on and enabled, Firefox cannot use GDI so DirectWrite will be used regardless of the setting for gfx.font_rendering.directwrite.enabled preference. However, the preference does work with hardware acceleration disabled, or if you’re using D3D9 hardware acceleration.
- Restart Firefox.
Once restarted, the font will be rendered as GDI clearly and smoothly. However, do note that the trick actually disable the hardware acceleration support for most 2D items such as fonts, which unavoidable will affect the speed and performance of 2D rendering of text and widgets. If you intend to use hardware acceleration in Firefox, here’s another alternative workaround to fix the font issue in Firefox 4, but may work or may not work for your system depending on graphics processing unit (GPU) configuration.
The trick is to disable and turn for anisotropic filtering in the GPU control panel, at least for Mozilla Firefox application. How’s how to disable anisotropic filtering in Mozilla Firefox for system using nVidia graphics card:
- Open nVidia Control Panel (Right click on Desktop or go to Control Panel -> Appearance and Personalization).
- Go to Adjust image settings with preview, and select the radio button for Use the advanced 3D image settings.

- Then, click on Take me there or go to Manage 3D settings.
- Under Global Settings tab, ensure that Anisotropic filtering is set to Application-controlled.
- Go to Program Settings tab, and select Mozilla Firefox from the “Select a program to customize” drop down list.
Note: If Mozilla Firefox is not found, manually add it in by browsing to its firefox.exe executable.
- Set the Anisotropic filtering to Off for Mozilla Firefox.

- Restart Firefox.
Tip: It may be possible to revert back to “Let the 3D application decide” for “Adjust image settings with preview” if you don’t restart the Firefox often.
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Thanks for the guide!, I upgraded my video card and realized my text appeared fuzzy in FF. I was going crazy because I couldn’t figured out how to fix it! Now it looks normal. Thanks!
@ Giang
You either need new glasses, or you're still using a CRT monitor.
@ Artem
Agreed. Using JPG for GUI screenshots is a VERY bad idea. PNG is a must.
@ noname
Thanks, man! Those settings really work, at least on my Windows 7 system.
DUDE,
1. mozilla.widget.render-mode is already removed since beta 7 & no longer use anymore.
2. You may still enable Hardware Acceleration on FF4 using Direct3D 9 on Windows 7/Vista without the blur font problem on D2D.
about:config
gfx.direct2d.disabled;true
layers.acceleration.disabled;false
layers.prefer-d3d9;true
I was able to correct this and still have hardware acceleration without the Anti-aliasing addon. The issue seems to be that during an upgrade from 3.x, the 'key' that controls DirectWrite may not be added.
To see if this is your problem type in 'about:support' (without the quotes) in the Firefox address bar. You will get info about the browser. Under the section labeled Graphics, confirm that you have the following:
Direct2D enabled=true
DirectWrite enabled=true
If DirectWrite enabled=false, you will need to type 'about:config' (without the quotes into the address bar. This will take you to the Firefox config window. Look for the following key: mozilla.widget.render-mode
That key is probably not present. To add it, right-click on an empty section of that window, choose New, and then Integer. Type in 'mozilla.widget.render-mode' (without the quotes) and assign it a value of 6.
If you have this key and the value is anything other than 6, right click on the key and choose Modify, and change the value to 6
Close and reopen your browser, and your fonts should look better. You may want to type in 'about:support' again and confirm that DirectWrite enabled changed from false to true.
This worked on Windows 7; it's worth trying for other operating systems and *shouldn't* break anything regardless of whether it works or not.
Font redenring in my Firefox 4 RC1 seem OK, and it seem very good looking too
correction: it should be about:config
Thanks, corrected.
Did not need high res graphics to get the point here. Thanks for the tip about the hardware acceleration setting. On a PC with Windows' Font Smoothing set to Standard (which for some reason I think may be an exacerbating factor) Firefox 4 RC1 fonts looked dreadful from menus to web site content.With Acceleration turned off they look just as they did in Firefox 3.6.x. Tx.
I agree. Needs more PNG.
Guys, your screenshots are UGLY.
Have you ever heard about PNG format?