You can try to switch off this feature completely:
- In the Location bar, type about:config, and press EnterReturn.
- The about:config "This might void your warranty!" warning page may appear. Click
I'll be careful, I promise!
, to continue to the about:config page.
- Search for the preference browser.urlbar.maxRichResults.
- Double-click the browser.urlbar.maxRichResults preference and enter a value of -1.
- From the menu at the top of the Firefox windowbar, select FileFirefox and then select the ExitQuit FirefoxQuit menu item.
- Restart Firefox again.
Now when you type in the Location bar, no list of results will be shown.