Below are 2 performance tweaks that should get your Firefox starting up and running just as it should be.

Defrag / Clean the Firefox SQLite Database

One way to increase the speed in which Firefox runs and opreates is to clean (Defrag) the Firefox SQLite Database.

To do this you need to :

   1. Goto "Tools | Error Console" within Firefox.
   2. Within the Code box enter the following : Components.classes["@mozilla.org/browser/nav-history-service;1"].getService(Components.interfaces.nsPIPlacesDatabase).DBConnection.executeSimpleSQL("VACUUM");
   3. Click Evaluate.

Firefox will appear to freeze shortly. Once complete your Firefox SQLite DB should be defragmented and the broswers performance improved.

Enable HTTP Pipelining

Normally when a browser makes a request to a web page it does so 1 at a time. HTTP Pipelining allows the browser to make several at once.
This of course can greatly increase you browsers performance.
In addition to this we will also change the amount of time Firefox takes to process information once it has been received.

Below are the required steps :

   1. Within your Firefox address bar type “about:config” and hit return.
   2. In the filter bar type "pipelining" and hit enter
   3. Change the following entries by right clicking on them and choosing Modify
          * Set “network.http.pipelining” to “true”
          * Set “network.http.proxy.pipelining” to “true”
          * Set “network.http.pipelining.maxrequests” to 8 (anything higher will be ignored)    
   4. Right click in the empty white area within Firefox and select "New > Integer". Name it “nglayout.initialpaint.delay” and set its value to "0".