So I’ve been playing around with the Firefox 3.0 Beta 1 download today. But I’m somewhat concerned by what I can only describe is a regression in font rendering. Here’s an image to illustrate.

On the left is Firefox 2 on my Ubuntu system. On the right is Firefox 3 beta 1. In both cases, I use the autohinter with slight hinting, and the font you actually see is Droid Sans. You can notice, however, that the the image on the right exhibits more color fringing than that on the left. In particular, look at the vertical stems of letters like ‘h’ and ‘i’. The right image shows a much more salient blue fringe.
I double checked to see if maybe the FF beta comes with its own copy of freetype or pango or cairo, but it looks like it’s linking the system copies. That means it’s somehow using LCD filtering, but specifying a different color filter? Anyhow, here’s to hoping that it doesn’t make it into the final release. Or that I’m just missing something.
Update: Looks like someone beat me to reporting it.