Does anyone else face minor lags here & there?

I bought this phone 11 months ago and since then i am facing minor stutter in animation in whatsapp app, settings app, camera app, safari...etc. I got ios reinstalled twice from the service center they also ran diagnostics 5 times but still the same problem persists. Usually the device is smooth but sometimes stutter happens and the stutter is .5sec/.25sec long.

is minor stuttering common? Please help.