There is an article on "Improve the Performance of Your MDAC Application" by Suresh Kannan that can be found on the Ms Data Access website. This article contains a lot of performance tips.
•Bind columns to field objects when looping through the records
•Use cursor-based updating only if needed
•Use a stored procedure with output parameters instead of singleton selects
•If you have to use a cursor, use the Collect methods for singleton selects
•Query only for the data you need
•Choose your cursor location, cursor type, and lock type with care
•Tune your Recordset CacheSizeproperty
•Release your ADO objects ASAP
•Describe command parameters yourself
•Dissociate your client cursor from the connection for R/O and long use scenarios
•Use adExecuteNoRecords option for non-row returning commands
•Use Connection::Execute for single execution
A detailed explanation of these tips can be found on the Ms website.