I am a software developer. I don't see how going from 2K to 1080p amounts to "optimizations they've added work".
Because 40fps at 1080p is still better than 6fps at any resolution. I can easily see optimizations getting rid of one cap but still leaving other issues. If CIGs optimizations were enough to...say...get rid of limitations introduced because of the poor network coding (or at least mitigate it), that could still leave performance issues due to graphical resolution which may still indicate a performance cap.
A lot of people were complaining about poor performance irrespective of resolution. If resolution is now a factor, that....to me...indicates an improvement in performance.
The most that can be said is that the performances can't be compared on a like to like basis. That's important...but ultimately, the only measure of import is whether the game plays well for most players. In 3.0...it didn't. I think we can expect some degree of improvement in 3.1but it is too early to judge how much of an improvement there is. As I said, for all that he claimed performance had improved, the video still appeared jerky in places...to me anyway.