Querying data from your data source can occasionally encounter some slowness when working with larger databases or repetitive queries of medium to larger data sources. By default, the CData drivers have a Pagesize which varies between each data source but can be raised to a higher number of rows. For larger databases, it can be best to raise the Pagesize field to a higher number depending on the number of rows contained in the data source. For example, when querying a database with 4000 rows, having the Pagesize raised to a value such as 2000 instead of the default (I.e., 1000) will result in two total requests instead of four.
Raising this field will typically result in higher memory allocated per page consumed but should typically improve performance. Query performance issues can be difficult to troubleshoot, but this is a good place to start if you are querying large databases.