Mario tinkerer extraordinaire Kaze Emanuar has come up with an improved way to run Mario 64 at a silky-smooth 60FPS, in widescreen.
While that sounds like an easy thing to do — just double the frame rate! — doing that speeds up everything (the game originally ran at between 20-30fps), so Kaze had to do some tricks like only triggering the game's physics every second frame and interpolating the camera's position so that it's always in the right spot.
The mod itself isn't new, but previous versions had some issues; this one is pretty much good to go.
The result is this very modern-looking version of Mario 64, which is exactly what you'd want from an official remaster.
If you want to try it out, there are download instructions on that video's YouTube page.