Slow bank reconciliation

Sage 300 Premium v 2019 PU1

In the last few months the bank reconciliation on one of the banks has become painfully slow again.

We have cleared lots of history previously - the history only goes back 2.5 fiscal years at this point, up until a few years ago it had decades and was working OK.

I took a quick look at the BKTRAND table and this particular bank only has about 8000 records related it (of 9400 total) at this point - that doesn't seem like a lot?

Would that not be where most of the history clearing takes place?

From what I can see, clearing another fiscal year would get rid of about 3500 records.

Any ideas on why this could be going on other than more history clearing? I like to be able to look back a few years at least...