S4 and 4.2.2: Reason for the lag?

This topic has been talked into the ground, but here's my thoughts anyway.

Before the launch of the S4, Apple had made the claim more or less that most Android phones don't launch with the current version of the software or that most Android phones aren't running the latest version right?

Well, lo and behold, Samsung launches the phone with the most up to date version avaialble. This certainly takes a bit of wind out of Apples comment, at least in regards to Samsung.

This swift revealing of the S4 running 4.2.2 makes me wonder this: What if Samsung simply shoehorned the newest version on the S4 without any optimizations nessacary to ensure a smoother operation?

I realize most people have noticed a marked improvement in performance by simply disabling some of the eye tracking features of the S4, but it still makes me wonder if Samsung may have simply needed more time to smooth out the hiccups before hand.

Thoughts on this matter?