the first video looks totally normal to me, i dont see any delay.
the second video looks quite strange. here i can see that something is slower than it should - and, it is not even constant but seems to happen at random.
let me add that i do not see these things on my systems anyway. because i do drag windows fully since ever, this looks much better than dragging a dumb emtpy rect anyway.
the blinking menu bullshit is also turned off here globally (i dont even know how to turn that on, when i think about it)
so i think that if you would just get rid of these functions OS-wide, you might no longer notice any anomalies in this app (which i can not explain)