You can change the number of lines Firefox scrolls in the about:config page, the variable will be called "mousewheel.min_line_scroll_amount", try changing it from 5 to 60, or whatever suits you.

In order to change your Firefox Configuration please do the following steps :

1. In the Location bar, type about:config and press Enter. The about:config "This might void your warranty!" warning page may appear.
2. Click I'll be careful, I promise! to continue to the about:config page.

You could try changing one (or both) of these hidden settings:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste wheel and pause while the list is filtered

(3A) Double-click the mousewheel.default.delta_multiplier_y preference and type in a higher value to make each movement of the wheel cover more ground. For example, you could try 300 or 500. You can keep this tab open and experiment with scrolling in a different tab until you find a value that gives you the speed you're looking for.

(3B) Double-click the mousewheel.system_scroll_override_on_root_content.vertical.factor preference and type in a higher value. For example, try changing 200 to 500. You can keep this tab open and experiment with scrolling in a different tab until you find a value that gives you the speed you're looking for.

I'm not sure I understand the reason there are two such similar preferences. Do either of them do what you want?

These two responses worked great! I think I need to go back and rejigger it, because now it's too fast, but I know what to do, now. Thanks to both of you.

You can also try to modify the value of the general.smoothScroll.mouseWheel.durationMaxMS pref on the about:config page to see if that makes a difference with smooth scrolling enabled.