first step for you to speed up your internet connecton is in address bar just type "about:config" then it will be shown everything about firefox configuration.
then just find the path below:
network.http.pipelining
network.http.proxy.pipelining
network.http.pipelining.maxrequests
then Set "network.http.pipelining" to "true" after that
Set "network.http.proxy.pipelining" to "true" next step  is you just changed the value
Set "network.http.pipelining.maxrequests" and make request to50 or smaller
tha last step you must make a ninteger just right klik and choose new integer
and named "nglayout.initialpaint.delay" and make the value "0"
 finally just checked it by resart first your browser.
enjoy your new connection speed