I bought a nokia 6 about 3 months back and it was working fine until a system upgrade came in and after that its being continually lagging. even it take about 2-5 seconds for the FB messenger to load up. Unlocking with fingerprint takes 1-3 seconds.
I haven't installed any battery saver or any 3rd party system performance related apps.
+ Sometimes when I take a picture with the camera it looks like video buffering. getting stuck etc;
is this related to phone encryption? if it is let me know how to de-crypt it.
This is the worst experience of using smart phones so far. I have used several smart phones and I got nokia because I needed an upgrade and better performance. however its making so much issues. not even lagging. I'm missing calls also. some emergency calls are also missed. I checked with the service provider also which they confirmed no issue from their end and confirmed that is is something wrong with the phone which made me reset the phone several times but no use at all. Issues are always there.
A too slow or defective SD memory card can cause all sorts of trouble.
(Even a UHS-1 speed class U3 is much slower than the phone's memory).
The best performance and reliability of Nokia 6 is achieved without SD.
If the phone performs the way you describe without a SD memory card, if there's still more than 3GB free internal memory, if the first troubleshooting steps: Restart > soft reset > factory reset does not resolve the issue, then please refer to the point of sale or a care point.