Comment 12 for bug 271933

To elaborate on Anders' point, we have now had several people confirm that the distro-shipped Firefox builds for x86_64 are behaving this way, even though our own builds on the same systems don't seem to. We've seen it on multiple distros, too, so I don't think it's something Ubuntu-specific, and nothing in the Ubuntu-specific patches for Firefox leaps out as a candidate; it really looks like something to do with the build platform, if only because it doesn't look particularly like anything ELSE. :)