Update after talking to Mozilla graphics hacker Joe Drew:
What I wrote above used to be true, but in current versions of Windows/Firefox these bugs have been fixed, and what you're seeing is probably the intended rendering.
The reason it looks blurry is that Microsoft's accelerated DirectWrite API uses different font rendering than the old GDI API. The DirectWrite rendering is less agressively hinted, and looks more like Mac OS X font rendering.
> The reason it looks blurry is that Microsoft's accelerated DirectWrite API uses different font rendering than the old GDI API.
Oh. Well, that sucks, because it means that I have to choose between hardware acceleration and readable fonts.
> If you don't like the look of the text rendering on our system [...]
That makes no sense. First, it's for Vista and not Windows 7, and second, I've already tuned Cleartype on my system. Even if it's possible to change my settings so it looks good in Firefox with hardware acceleration, changing it means it will look bad everywhere else.
What I wrote above used to be true, but in current versions of Windows/Firefox these bugs have been fixed, and what you're seeing is probably the intended rendering.
The reason it looks blurry is that Microsoft's accelerated DirectWrite API uses different font rendering than the old GDI API. The DirectWrite rendering is less agressively hinted, and looks more like Mac OS X font rendering.
If you don't like the look of the text rendering on our system, try: http://www.microsoft.com/typography/ClearType/tuner/tune.asp...