That's just how bad Nintendo is at porting their own games! There's constant FPS dips, and the input lag is so bad that you can literally see the delay without needing any equipment to measure it. It's so bad in Mario 64 that it renders the game unplayable, leaving you with two games can actually be played (but just barely so. They still have input lag, and it's much more difficult to control the water gun in Sunshine since the Switch doesn't have analog triggers).

I much rather play these games in an emulator. At least they'll run properly.

https://youtu.be/0q5qOYp9ihY