On nvidia optimus laptops you have an onboard gpu and a "proper" gpu. The onboard saves battery life, but the proper one gives much better performance in 3d games.

When using linux, launch minecraft on the "proper" gpu rather than the onboard gpu using the command optirun, like this:

$ optirun java -jar MinecraftLauncher.jar

This works with the old launcher but not with the new one. The reason is because the new launcher launches minecraft as a separate background process and then exists. Since optirun is tied to the launcher process it will also exit when the launcher process exists. Since optirun needs to be running for the game to work with the "proper" GPU this causes the game to crash.

The old launcher does not do this and the above will work just fine with the old launcher.

Someone could make a workaround by writing a "launcher for the launcher" and making sure that this launcher does not exit until minecraft exists, and then you run the "launcher for the launcher" using optirun. I will do this if I have to, but that seems like weird thing to have to do, and really, the proper thing to do coding-wise would be for the launcher process to replace itself with the game process instead of launching the game as a separate process and then exiting.