Firefox has a great search feature based on Command-F (Mac) or Control-F (Windows).
You get a cute little text box at the bottom of the screen which allows you to search the whole page.
Firefox Find - Command-F
Subsequently Command-G works just fine to take you down through the page.
Just ' (apostrophe) alone will bring up the Quick Find box. It looks almost the same but isn't. Quick Find only searches URLs (a nice extra almost undocumented feature).