It is rare, but some websites can cause a silent crash that doesn't generate a crash dialog. If you want to share the URL, perhaps someone here can confirm that they get the same problem. Could you try using Firefox's Safe Mode for a while? That's a standard diagnostic tool that deactivates some of the features of Firefox most likely to cause problems, including extensions, hardware acceleration of graphics, JavaScript compilers, and various custom settings. You can restart Firefox in Safe Mode using Help > Restart with Add-ons Disabled ''(Flash and other plugins still run)'' In the dialog, click "Start in Safe Mode" (''not'' Reset) Any difference (not sure how long it will take before you know whether it is working better)?