Minecraft only at 18 fps although drivers are up to date?

I already asked the question yesterday at night, but nobody answered it and I would like to add a few things:

I installed the latest drivers and then I was able to play Minecraft normally at around 400 fps. Today I have the same problem again.

16GB RAM, Vega 64, Ryzen 2600x

It would be very nice if someone could help me. Should I reinstall Java?

Take a look at what workload your PC has and whether you have allocated enough RAM

I assigned 6GB RAM and in the task manager everything is at max 40%

Which task manager do you have, win10 or 7?

10

I just uploaded 2 pictures that should be displayed immediately

Then do you know what I could do?

Maybe turn off V-Sync then everything stops jerking for me.