You can do this in the configuration settings, to do it, at the address bar type "about:config" (without quotation) then press enter.
Then you'll be prompted , click "I'll be careful, I promise!"
All you have to do is set the "value" of "preference name", remember you have to set them depends of your broadband connections and hardware of your computer and only include some of the settings that would affect performance.
Common to all configurations
"network.http.pipelining" set value to "true"
"network.http.proxy.pipelining" set value to "true"
"network.http.pipelining.maxrequests" set value to "8"
"content.notify.backoffcount" set value to "5"
"plugin.expose_full_path" set value to "true"
"ui.submenuDelay" set value to "0"
Fast Computer Fast Connection
"content.interrupt.parsing" set value to "true"
"content.max.tokenizing.time" set value to "2250000"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"nglayout.initialpaint.delay" set value to "0"
"network.http.max-connections" set value to "48"
"network.http.max-connections-per-server" set value to "16"
"network.http.max-persistent-connections-per-proxy" set value to "16"
"network.http.max-persistent-connections-per-server" set value to "8"
"browser.cache.memory.capacity" set value to "65536"
note: Firefox is allocated 4096 KB of memory by default and in this configuration we give it roughly 65MB as denoted by the last line. This can be changed according to what is used.
Fast Computer, Slower Connection
"content.max.tokenizing.time" set value to "2250000"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"network.http.max-connections" set value to "48"
"network.http.max-connections-per-server" set value to "16"
"network.http.max-persistent-connections-per-proxy" set value to "16
"network.http.max-persistent-connections-per-server" set value to "8"
"nglayout.initialpaint.delay" set value to "0"
"browser.cache.memory.capacity" set value to 65536
notes: This configuration is more suited to people without ultra
fast connections. We are not talking about dial-up connections but
slower DSL/Cable connections.
Fast Computer, Slow Connection
"browser.xul.error_pages.enabled" set value to "true"
"content.interrupt.parsing" set value to "true"
"content.max.tokenizing.time" set value to "3000000"
"content.maxtextrun" set value to "8191"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"network.http.max-connections" set value to "32"
"network.http.max-connections-per-server" set value to "8"
"network.http.max-persistent-connections-per-proxy" set value to "8"
"network.http.max-persistent-connections-per-server" set value to "4"
"nglayout.initialpaint.delay" set value to "0"
"browser.cache.memory.capacity" set value to "65536"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"network.http.max-connections" set value to "32"
"network.http.max-connections-per-server" set value to "8"
"network.http.max-persistent-connections-per-proxy" set value to "8"
"network.http.max-persistent-connections-per-server" set value to "4"
"nglayout.initialpaint.delay" set value to "0"
"browser.cache.memory.capacity" set value to "65536"
Slow Computer, Fast Connection
"content.max.tokenizing.time" set value to "3000000"
"content.notify.backoffcount" set value to "5"
"content.notify.interval" set value to "1000000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "1000000"
"content.maxtextrun" set value to "4095"
"nglayout.initialpaint.delay" set value to "1000"
"network.http.max-connections" set value to "48"
"network.http.max-connections-per-server" set value to "16"
"network.http.max-persistent-connections-per-proxy" set value to 16"
"network.http.max-persistent-connections-per-server" set value to "8"
"content.max.tokenizing.time" set value to "3000000"
"content.notify.backoffcount" set value to "5"
"content.notify.interval" set value to "1000000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "1000000"
"content.maxtextrun" set value to "4095"
"nglayout.initialpaint.delay" set value to "1000"
"network.http.max-connections" set value to "48"
"network.http.max-connections-per-server" set value to "16"
"network.http.max-persistent-connections-per-proxy" set value to 16"
"network.http.max-persistent-connections-per-server" set value to "8"
"dom.disable_window_status_change" set value to "true"
notes: One of the changes made for this particular configuration is the final line where the status bar is disabled for changing web pages to save processor time.
Slow Computer, Slow Connection
"content.max.tokenizing.time" set value to "2250000"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"nglayout.initialpaint.delay" set value to "750"
"network.http.max-connections" set value to "32"
"network.http.max-connections-per-server" set value to "8"
"network.http.max-persistent-connections-per-proxy" set value to "8"
"network.http.max-persistent-connections-per-server" set value to "4"
"dom.disable_window_status_change" set value to "true"
"content.notify.interval" set value to "750000"
"content.notify.ontimer" set value to "true"
"content.switch.threshold" set value to "750000"
"nglayout.initialpaint.delay" set value to "750"
"network.http.max-connections" set value to "32"
"network.http.max-connections-per-server" set value to "8"
"network.http.max-persistent-connections-per-proxy" set value to "8"
"network.http.max-persistent-connections-per-server" set value to "4"
"dom.disable_window_status_change" set value to "true"
notes: We have entered the doldrums of the dial-up user.