There is no built-in setting for the spacing between menu items. I can give you a quick short-term workaround, but a more durable solution will require more work. '''''Temporary Fix''''' For testing purposes, the developers left a preference in Firefox 89 to switch between new style and old style menus: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. (2) In the search box in the page, type or paste '''browser.proton.contextmenus.enabled''' and pause while the list is filtered (3) Double-click the preference to switch between '''true''' (new style) and '''false''' (old style) ''Some menus may be cut off or sized incorrectly after this change until the next time you do a normal exit/restart of Firefox.'' '''''Longer Term Community Workaround''''' This involves setting up a userChrome.css file. The full instructions are in the following thread: https://support.mozilla.org/questions/1337841