Firefox 3,5 was recently released. I immediately downloaded it, hoping for a nice upgrade. Instead, I'm getting memory errors several times a day (I have not changed my browsing habits). I have, therefore, switched almost entirely to Opera. It's significanty faster, though it lacks a few features I liked. This may be a permanent switch. Although I still like Firefox (and much prefer Foxkeh to a red "O"), I am not able to interrupt my browsing session several times a day. As Firefox is such and icon of the open source/free software movement, I am hopeful that the issue will soon be resolved.
