If you need to append small amounts of data to an ODBC table, open the recordset by ORing in the DB_APPENDONLY flag. This will avoid the population of the dynaset with the bookmarks of all the records in the table.
If you're trying to append a lot of data to an ODBC table that is already stored in an .MDB table, then use the technique suggested under Batching Insertions elsewhere in this document.