With increase in number of regions in a cluster the number of steps taken by balancer in 30 sec (default balancer runtime) reduces noticeably. The following is the number of steps taken with by balancer with region loads set and running it without the loads being set i.e. cost functions using region loads are not fully exercised.
As one would expect the reduced number of steps also makes the balancer take long time to get to an optimal cost. Note that only 2 data points were used in the region load histogram while in practice 15 region load data points are remembered.