I decided to give the ramdisk another go. I'm using Dataram RAMDisk freebie.
I made the mistake before of setting it to auto save the image on shutdown. This resulted in horrible shutdown times. What I'm doing now is only saving the image manually if I have some significant Firefox update, like updating a bunch of AddOns. My bookmarks and passwords I can save with SyncPlaces instead of saving in the image.
It may not load much faster than standard FF off a fast HD, but if your HD is busy, like doing a video mux, then this method kicks ass.
The configuration tool for the Ramdisk doesn't have a setting to autoload on Windows startup, but I just put a shortcut in the Startup folder and have it set to load the image file when the ramdisk starts. The thing opening on the desktop will remind me to start the Ramdisk.