Microsoft and Sumo Digital have released the first update for Crackdown 3. According to the release notes, this patch improves performance during particularly long co-op sessions and allows co-op campaigns should now prompt for an empty save slot to avoid overwriting existing world data, though it did not resolve the 30fps lock issue that players have reported.
Source: N4G PC First Crackdown 3 update improves co-op performance, full patch notes revealed