I have had this happen and I thought it might have been a certain app but like you said it was OK before the oreo update
So there must be a bug or the apps that you are using may need updating so that they are compatible with oreo, hopefully Samsung will take note and fix the problem if it is the oreo update causing the problem.
does anyone know how to clear cache & data to navigation bar ???
did they fix in CRD7 laggy nav bar ??
p.s the nav bar does not always lagg but sometimes it does like you press the buttons but nothing happens (but the buttons does not freeze ) simple you press but nothing reacts the screen does not freeze .....
did you have this issue >?
i did clear samsung experience data & cache hope will fix---not fixed
wipe cache on prevesious update crc7 oreo --did not fix
curent firmware crd1
this did not happen in nougat
I've attched screens for better understanding
in rest the phone works perfect
maybe apps like badoo and tinder do this social apps .. ?