Yes, that is it.
But in that process, when does that happen?
Does it only happen when the coins are old enough, which is after the 1 week wait time, or when the coins can create a valid PoS block.
I had a look into the code:
The process is launch every block but the calculation and split is done after 1 week of coin age.
The perf problem should be into the election test as it tests every coins, it multiply the delay and load.
Now it is to find out were and why because it has to be really quick .......