The unresponsiveness might be memory related, though it's impossible to know for sure. Have you tried altering the 'swappiness' sysctl setting? The default it 6

The unresponsiveness might be memory related, though it's impossible to know for sure. Have you tried altering the 'swappiness' sysctl setting? The default it 60 out of 100, where higher means earlier swapping to disk. Another culprit might be too high dirty page thresholds. There's also the drastic step of deleting your firefox profile folder and starting over... Here's some links that might help: https://wiki.archlinux.org/index.php/Swap#Performance_Tuning https://wiki.archlinux.org/index.php/Swap#Performance_Tuning https://wiki.archlinux.org/index.php/Sysctl#Virtual_memory https://wiki.archlinux.org/index.php/Sysctl#Virtual_memory https://wiki.archlinux.org/index.php/Firefox/Tweaks#Performance https://wiki.archlinux.org/index.php/Firefox/Tweaks#Performa... EDIT: and one more... https://wiki.archlinux.org/index.php/Firefox/Profile_on_RAM https://wiki.archlinux.org/index.php/Firefox/Profile_on_RAM