RE: 2 million transactions for one customer is freezing GP
UriZ, we had a similar issue after upgrading to Dynamics GP 2018. Sorry, I don't have any of the research links I previously found but know that the stored procedures that run when Receivables Transaction Inquiry (Document or Customer) is opened does not have a TOP limit on the transactions it pulls in so it pulls them ALL
In our case it would hang the client for a couple minutes...and we have a VERY ROBUST server with over 3 million receivables transactions. I also read that this has already reported to Microsoft.
There are at least two things to consider: The initial window opening and filter criteria.In our case I used Visual Studio to cancel the initial data pull when the window opens. This would also work for you, even with all transactions under a single customer. Secondly, I also force our users to make a filtered selection so they don't attempt retrieving all historical records. This could also work for you but since all are under a single customer, you may want to force a narrower date range or other tailored filter requirements to limit the records pulled at a time. For us, the window opens immediately and is ready for a range value to be entered. Our people are often just searching for a single document so this works fantastic.
If you don't have a Visual Studio solution you may be able to use VBA. It has been too long since I looked at VBA to know if the procedures are available in that. I have attached a text file with my Visual Studio code as a starting point if that helps.
ReceivablesTransactionInquiry.txt