I'm gonna be that guy to bring this up, but PS4's floor demo's were actually running on PS4 hardware. Which does not have final OS more than likely and frame rate can change until launch of the games which is late October through December.
Xbox One games weren't even running on the xbox hardware;
http://www.slashgear.com/xbox-one-e3-demos-were-played-on-windows-gaming-pcs-15286627/
Yea, so some of these playthrough's will be smoother and ironed out before launch. I remember the first play through for the first Darksiders locked up, and had to be restarted, and slowed down a lot. But at launch all we had for problems mostly was screen tearing.
Look at the lock ups at this E3, Assassins creed locked up and that was running off of Ubisofts own set up. EA had to restart their demo because it crashed.
I would take these so called mini preview's of these unfinished games with a grain of salt. For both companies, but mostly people ragging on the whole 30 fps crap get over it.
At least Sony First party games were being more genuine in running on their own hardware, where Microsoft was demoing their's from Windows 7 box's! As if they don't trust the performance of their latest OS?
They fact that they basically showed game demo's like Sony did in February, Does indicate that they are indeed couple month's behind.