I note that you cannot fix this. Can I make a proposal for you?
Without understanding exactly how Kashflow works, it does seem as though there might be a simple way to fix this. If you imaging that the nominal ledger reports are made up of two elements:
the opening balance
2. Transactions in the year.
As Kashflow does not strictly close periods, I believe that when Kashflow is calculating the opening balance it needs to compute this figure for all transactions in each nominal ledger from the initial start date to the last year end. This is a lot of data and a lot of calculating. Would it not be easier if Kashflow could formerly close a period at a year end and for the closing balance to be carried forward and entered as a one figure opening balance in each nominal account. Traditionally, this is how other bookkeeping packages work and would reduce processing time massively.
Contact me if you need to link this to the Support ticket that cannot be fixed.