I have noticed that an upgrade to a new version of Android like 8 to 9 will often times cause some problems. I know my Nokia 6.1 became started glitching and I noticed some lag at swiping. On the advice of the Nokia support forum I backed up the phone, did a reset, then restored the info and everything was fine after that. I've seen that same advice on other forums for other phones as well. Might be something to try.