During my day at home I noticed that the Firefox is awful slow when it comes to browsing on sites. A little google about slow performance showed that firefox is delivered with ipv6 enabled by default since the beginning.
Disabling this will speed up firefox massivly (atleast for me)
Type in following url “about:config” and search for “network.dns.disableIPv6” and set it to true. Restart and check if FF is faster now.