Major fps drop when switching from 1.21.11 to 26.1 or 26.1.1

usually i get around 500 fps average on minecraft, but recently after upgrading my version from 1.21.11 to 26.1 ive noticed around a 5x - 5.5x drop in fps. on 1.21.11 i average 500 fps but on 26.1 i can barely reach 100 fps usually averaging around 80 fps. this isnt a computer issue too because i tried switching back to 1.21.11 and my fps instantly went back up to 500 but as soon as i switch to 26.1 my fps drops a LOT. ive included 2 images comparing my fps on 1.21.11 and 26.1 . all video settings and mods are the same on both versions. the screenshot showing 547 fps is on 1.21.11 and the screenshot showing 54 fps is the one on 26.1