Emulator is banned for all times that are within 10% of the existing record. If you are unsure of what this time is, contact a moderator

What does this exactly mean?

Example, if the record is 10 minutes, then an emulator run will not be accepted if it's 11 minutes or faster (10 minutes + 10% x (wr 10 minutes) = 11 minutes)

So emulator runs are fine, but once you get too fast (10% of the record) it won't be accepted. (If that makes sense)

But why is that? Like, are emulators faster during load times or something?

Probably to prevent any possible cheating or the emulator not being perfect are my guesses. Someone would be less likely to cheat if they are limited for their time (can't be #1 or a top time, so why bother cheating) --- maybe

I don't run the categories, so I don't actually know the reason(s).

It's more to do with the fact that emulating the game is unofficial. In an ideal world, we would outright ban emulated runs but as a community, we understand that it's a useful tool to get people into the speedrunning scene without any monetary investment. The 10% ban is to allow players to learn and get some respectable times on the leaderboard but if they intend to take it to the top level we insist on official hardware.