Low GPU Usage + unplayable stuttering

Ok so basically whenever im playing on minecraft 1.15.1 my GPU usage doesn't go above 25% and i only get like 40 and it stutters really bad. like basically freezing every 2 seconds.With 1.14.4 (with and without optifine) i got a minimum of 100 fps. (ignore i poor resolution of the vid, had to get it to 10mb lol)

 

Specs:

i7 7700k @5.0GHz

64gb DDR4 2700MHz

GTX 1070

3440x1440 Monitor

Windows 10 Pro x64