Apart from the time taken to load, what user is going to page through 500 pages on-screen?

I have been asked about this limit many times, and always there is no good reason for loading so many records at once. Usually, it’s a lack of understanding of the varieties of subfile processing, but sometimes it’s because the programmer wants to hold the complete database file in the subfile. Again – there is no good reason to do that.

Consider allowing the user to filter the database into the subfile by allowing her to enter selection criteria. The selection can be done by embedded SQL or by compare-and-ITER code. This, in combination with a self-extending subfile, will cut down the number of records selected to a manageable figure. Additionally, don’t load the subfile immediately on program entry, even if you are loading page by page, but instead allow the user to enter any filter values and then load after ENTER is pressed.