ios 9.3.5 lag/stutter

I am using iPhone 6 running ios 9.3.5 and I am experiencing some lag/stuttering frame drops issues on this device when i try to scroll big list like notifications list or big list of youtube videos especially TableViews from ios Component .

I went to the Apple service center also and they restored my device 2 times also.

But issue hasn't been fixed yet .

Now i restored to ios 9.3.4 the lag is somehow reduced , but now there are some apps in which there is lag present like Google+,YouTube,Instagram,FaceBook .

I have re-Installed these apps several from the AppStore but the lag is still there in these apps.

Please help me to fix this issue.