but surf the internet for a couple days without restarting Firefox (27.0.1) on Ubuntu (13.10) and Firefox still grinds to a half, taking more than half a second

but surf the internet for a couple days without restarting Firefox (27.0.1) on Ubuntu (13.10) and Firefox still grinds to a half, taking more than half a second to change tabs or register other UI input. Shrug, I do this all the time as I never restart the browser. And your timer test is WORKSFORME too :-/