So there is no fix for this yet.
The second is the POS calculation of interest multiply the quantity of transaction into the wallet because the processes separate in two part the old transaction creating two new transactions and so on every loop (increasing by 2^n the number of transaction by the time). Also if you connect to the precedent point ......
I do not understand what you mean by this.
I have not looked to the SLIM code but in POS code generally the process to calculates interest is:
if the coin is old enough
then take the transaction and calculates the interest
then take the total of the transaction + interest and
then create two new transaction with the half of the total (creating two new transaction)
then delete the old transaction.
This is the general process for POS, I think it is the same for SLIM, isn't it ?
So if SLIM uses the same schema, the number of transaction into wallet have a tendency to increase by 2^n and the performance dropping in parallel.