I was trying to make the point that the dominant factor becomes linear instead of logarithmic, but more accurately it's O(S log N) = O(N log N) because S (number of segments) is proportional to N (number of vectors).
Ah yeah that’s what I wanted to write but I guess I didn’t want to put words in your mouth, and stuck to what I could be certain about happening. We do all this work to throw away the unneeded bits in one situation and when comparing it to a slightly different situation go “huh some of that garbage would be kinda nice here”