Why is the CPU and GPU only used to 30% in a few games and I still don't have that many fps?

My CPU is in Minecraft for example. At 11% and my GPU at 40%. But I only have around 100 FPS and sometimes frame drops. I have already set RAM to 8GB.

What can be the reason?

This is mostly due to the fact that only one CPU core is used or Am is limited. In the case of Minecraft, this can be significantly improved with OptiFine.