Full disclosure: I'm predominantly a Chrome user on Windows, but I finally let Firefox download and install the latest version, 4.0. Considering this version has been in development forever, I frankly expected better.
It appears that they've "improved" text rendering by applying font smoothing or anti-aliasing across the entire user interface—not just the text displayed on the pages themselves, but also the text in menus, toolbars, and dialog boxes. Even the context menus use a re-hinted version of Segoe UI.
I think it's blurry and very difficult to read. How do I turn it off? I can't find anything in the Options dialog that looks useful. Perhaps it's something in
about:config, but I don't know enough about Firefox to know where to start looking. I can't imagine they would make such a dramatic change without providing the facility to revert to the classic rendering mode if the user so desired. Open source software is notorious for gratuitous customizability; here's a case where I would actually appreciate it.
Additionally, I've discovered that I frequently out-run its ability to process input. In every text entry field that I've come across, I've out-typed Firefox's ability to display each character. More than once, I've even managed to crash the browser trying to type, with only one tab loaded. I suspect this is related to the font rendering changes, as anti-aliasing requires more computing "umph". I'm hoping that if I find the button to turn that off, it'll fix the severe typing lag. But if anyone just so happens to have any other suggestions on how I might fix that, I'm all ears.
The machine in question is a Dual Xeon with 5 GB of RAM running Windows Server 2008 R2, 64-bit.