My 6S+ was also literally unusable after the iOS11 update. 5 second hangs on some actions, jittery scrolling. It improved after a few weeks. Not sure if it w

My 6S+ was also literally unusable after the iOS11 update. 5 second hangs on some actions, jittery scrolling. It improved after a few weeks. Not sure if it was an .x update that fixed it, or maybe it needed time to reindex (?) but it's fine now.