Minecraft fps low after reset?

I reset my PC and now I only have 25-20fps with Minecraft

If not in full screen, then around 100.

Before that, I had at least 60 in full screen, almost always over a hundred and sometimes over 300.

What could that be?

You had Optifine
You had your settings down and now they're back to normal

I have labymod. There's optifine and I have already optimized the settings

What CPU do you have?

Intel core i5 7400