Hi folks! I thought I'd post this here since I've heard of it happening to others. There is a chance that after the April console update your display settings will default to turn 50Hz on, even though your display is not a 50Hz display. The visual impact is likely fairly minimal for most users, but this is not the optimal refresh rate for displays in the U.S. running at 60-600Hz.
To check this (and fix it) go to:
Menu -> Settings -> Display & Sound. In here, uncheck the box for 50Hz.
This should fix any framerate or flickering issues you may be experiencing here in the US following the update!