Looping animation slows it down!

Hi. I have an animation I want to loop in order to better see how it would look like and what to change (it’s for a video game), and I found this method (https://pasteboard.co/I1ahRi0.png). When adding the Cycles modifier nothing happens, but when I use that submenu the animation does loop. However, it slows down the animation speed massively, as if it took more resources to loop it or if it had to process duplicate information. Any ideas on how to fix it, or what’s going on?