Q: My game is stuttering or FPS are low, help!
A: Open task manager and see if:
Your CPU is at (or near) 100% usage.
In the config: lower the CPU preset and/or disable world generation.
If that doesn't fix the problem increase the amount of RAM you have allocated for Minecraft. If you have over 4 world generator threads or more, you will probably want 8 GB of ram or more.
I didn't get any of that