I randomly started having problems that fps drops to 2 fps and I didn't know what was causing that but I checked the pastel graph that appears when you do shift+f3 and when and when fps started dropping to like 2 fps from 60 the pastel graph shows that the part named Tick started increasing and the game reacted by lowering the fps.

If you can fix this behavior it could be useful because you might be playing in multiplayer and you have to run and then this happens and you are unable to run away due to severe lag refusing to accept the run feature.