In Minecraft, without changing the settings, I have a lot less fps than a few days ago despite a good pc.
why is that?
It may be due to a missing Windows update or a missing driver update, but it can also be due to the fact that your processor and PC itself is dusty
You should see if:
your drivers (especially graphics drivers) are out of date
you have pending Windows updates
your FPS can be limited in the graphics settings
you are currently using your graphics card or onboard graphics (if available)
you can allocate more RAM to Minecraft
Minecraft brings more FPS in windowed mode
it is due to the RAM usage (in addition to Minecraft, just run the task manager)
you can set your chunks down (e.g. To 8 or 4 chunks)