Low fps and good computer, and extremely unstable framerate

well, recently i started experiencing a lot of stutter / lag in minecraft (just in java edition, in bedrock it runs 100% smooth) and i did pretty much everything i could, but nothing helped.

in the f3 framerate, it always shows something like "200/40", that means the game is having a extremely unstable framerate, and that happens the entire time.

i use a gtx 1650, i3 9100f, h310m motherboard, 8gb ram hyperx and a 480gb ssd.

and apparently, as some tests that u/jpie726 made (thanks tho) the framerate changes a lot when going or looking for different directions of the map.

and it cant be my pc i think, because bedrock runs 100% perfect without any flaw,