For someone that's all about 'posting facts' you sure do like to make shit up.
The framerate in ZombiU does not nose dive when thunder strikes.
https://youtu.be/CXUdIYjKpRU?t=19m57s
I have the game and yes it does. For a split second the framerate nose dives causing stuttering. If you move the camera while it happens you notice a split second of freeze lag which is caused by the framerate suddenly dropping a lot.
It happens on WiiU and it happens here in the pc version where I'm otherwise getting a solid 144fps. Logging the event I can see drops from 144 to 80.
So please fuck off with your acusations.