^Maybe the slow rise is due to the constant change in the formwork. It looks like the floor opennings change at each level, thus the change in formwork takes a little time to reconstruct before they start pouring the next level.
At least it is getting built.
We don't know for sure if the Busan Lotte tower is even being built due to no thread activity here and at SSC. It is supposed to be the 3rd or 2nd highest in the world and yet, no pics since its inception or news since March.