For directories with a huge number of games (eg my MAME folder has over 2,000 games), you don't scroll thru the list - you just press the hotkey, bring up the "jump to" option, and jump directly to, eg, the letter H, or the letter S instantly.
No need for sub folders, and doesn't matter if there are 10 or 10,000 games in the folder - you get there instantly 👍

Forgot to add - if you hold the down (or up) button in for 5 seconds, it accelerates the speed it scrolls thru the game list too.