https://www.curseforge.com/minecraft/mc-mods/g4mespeed
Crashes on boot

As far as I know you can use carpet mod to change game speed.
But immptl has some compatibility issues with carpet as well.

As far as I know you can use carpet mod to change game speed. But immptl has some compatibility issues with carpet as well.

Carpet mod does it a bit differently, for example when you slow down the game your character slows down too, but when you speed it up, player doesn't become faster