When using my crappy netbook I found that I needed to use firefox’s fullscreen thingy (f11), but because my netbook is so slow it goes laggy when the address bar goes back up. So to disable the animations goto “about:config” -> then type into the search “fullscreen” to disable the animation set “browser.fullscreen.animateUp” to 0 from 1. This will disable the cool but laggy animation. Also you can make the menu stay ontop by changing the “browser.
If you have installed Linux and you used firefox, you may have noticed that pressing backspace dose not take you back one page, but takes you up to the top of the page. To fix this simply type into the address bar of firefox about:config And search “backspace” change that from ‘1’ to ‘0’ :D