Everything happens faster when you step up in competition. Gaps close faster, defenders recover faster, defensive lines come at you faster, etc, etc, etc.
That said, Zach was making throws very few guys can make, period. The talent level of his receivers and the defenders doesn’t much matter when there are only a handful of guys in all of college football who could make the same throws.
However, it’s still legitimate to wonder if he can keep himself settled enough to make those same throws when everything around him is happening much faster than he’s used to.