They just display a tiny bit of text and images, they should switch between screens at 60fps, not 2s per click.
I think this is intentional. They want you to take time looking at the pictures so you might think “you know what, actually I’d like some of those fries as well” by making it hard to just quickly select what you want and leave.
I wouldn’t even be surprised if there’s a psychological effect where you feel like ordering more makes this tedious ordering process more worthy. I mean why go through 2 minutes of clicking and waiting just for one stupid cheeseburger.