In my application (MapWinGis.ocx 184.108.40.206, windows 10 64, Access 32 Bit, vba) I sometimes need to create an index of unique values by:
objShape.Categories.Generate 0, ctUniqueValues, 0
This works if there are not too many elements in the shapefile. But it's painfully slow.
Yesterday I had to revert my application to MapWinGis.ocx 220.127.116.11 and the above code is much faster.