preload works for what it is made. It is not made to speed up firefox startup time. Firefox loads a bunch of sqlite files in your /home. This and other things might explain your slow startup time of firefox. One of the ways to speed up firefox is to put your ~/.mozilla in a tmpfs (doing it the right way, else you loose your data). This have been discussed somewhere I think. How else ? Please complain about Firefox for its slow startup time and not about preload for not speeding it up. Try chromium if you want quick startup time ;-)
