It'll make the delay worse. Just plugged it directly into the TV, and the PS4 into the switch. Now the mouse moves much better. Maybe driving in Saints Row: The Third is easier now. For some reason on foot, is easy, but driving was a pain.
The people getting a big delay, must have a very shitty setup, or a defective extender. I'm using a powerline adapter, so it should be more shitty then just ethernet.