FPS lag in all 1.13 and 1.14 versions

Hello. I've seen more posts about this issue but I couldn't seem to find a way to solve it. Every now and then it just happens that my game drops down to 15-50 FPS and it lags really bad. Sometimes it's smooth and then I move and this happens. I usually get over 100 fps.

Even though the specs aren't the best, I think they're more than enough to run this game. 8 chunks, fancy, no smooth lightning, max fps.

Let me know if you need more information to help me solve the issue. Thanks in advance