Extreme Minecraft lag?

So I haven't played minecraft in a few months and my friends are working on setting up a modded minecraft server. I got on minecraft to test out my single player world again and was greeted by 1-2 fps. I was able to play minecraft with 60+ fps a few months back and I know my computer can handle minecraft. I would like to fix this soon before the modded server opens. All help is appreciated.

Added (1). I can put the game in full screen and it works within the loaded area but once I try to go to a different area or load in a new part of the map it drops from 60 to 2 fps

Check your settings and if nothing works, play on the immediate version below through the launcher to see if problems persist.