The way it works is instructions need to be "translated" when emulating.
However, it's not a 1:1 translation, some instructions need to be split-up into multiple instructions that's compatible with the host machine.
So one Instruction on a console could equate to 3-4 instructions on the PC, hence you need orders of magnitude of CPU performance to run it.
Conversely, some games may use a ton of instructions where they aren't split up as heavily.
Another game may use allot of instructions that are split up allot, thus one emulated game will require more CPU performance from the PC doing the emulating, but still use the same amount of CPU horsepower on it's original system.
Another issue is emulation accuracy, you can bring down even the fastest of PC's if you built a 100% accurate SNES emulator, most emulators however don't push for such levels of emulation accuracy, but instead find a middle ground of "Good enough".
www.youtube.com/@Pemalite
