Mozilla will release Firefox 4 beta 4 on Monday, one of the new features in this release will be support for hardware-accelerated graphics:
Mozilla is planning on releasing Firefox beta 4 on Monday with two major new features: hardware-accelerated graphics for Windows users and tab sets, or better known as tab candy. Hardware-accelerated graphics done with Direct2D will not be turned on by default, as Mike Shaver, Mozilla's vice president of engineering, sent a tweet stating "b4 won't have D2D on by default after all; just not quite ready to send it to that many users. soon!"
If you wish to enable Direct2D rendering, you can follow Mozilla's instructions on their wiki, which consists of this:
Type "about:config" into the URL bar, type in "gfx.font" in the Filter box, set "gfx.font_rendering.directwrite.enabled" to true by double clicking. Then below that, right click and select New >> Integer, name it "mozilla.widget.render-mode" and set the value to 6 then restart the browser.