Here's a couple of useful info i learned after using emulators for a couple of weeks. This is by far not a tutorial, just things i wish i had known sooner.

YUZU (Switch)

This may vary from game to game, but from my experience seems that Yuzu gives better fps. The XCI roms are a bit bigger but don't require any firmware, instead Nsp does, but you can find the Firmware online pretty easily. Some game more demanding will run way better after activating some mods. Just open yuzu>help>Open Mods page and download what you need, the right click (L2) the game and select > Open Mod Data Location and past inside the (unzipped) mod.

Zelda - Breath of the wild is "kinda" playable on Switch but is way better to use the Wii U rom on Cemu (enable the FPS++ mod to fix the fps) - I can't give any link but the site where i find the best rom is "8bitsdown" (google it)

Cemu (Wii U)

You need some key codes (number and letters) but just google "Wii U keys" and past them in the txt Key file inside the Wii U folder. As yuzu some games works better with mods. Cemu > right click (L2) the game > modify the graphic package> Download the Updated package from the community> check any mod or cheats you want.

PCSX2QT (ps2)

Some roms may need the bios file. You can increase the resolution in graphic setting> internal resolution ( i use 3x native - 1080p)

Retroarch is also good for "clean" the graphics of old snes or psx games using shaders and filters (check these videos Link1 | link2) - BTW Retroarch is installable from emudeck too, after that just add the app to the library as non steam game.

That's it - Feel free to add more info below

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