Wasn't PC Supes quicker than the Flash? At his full speed he was wrecking civilizations just from his passage near said systems. He was moving so fast he was breaking every dimensional barrier (trying to save Supergirl IIRC) and was about to break through the final barrier (the gates of heaven itself) before the Presence intervened to stop him through the Spectre.
The guy was written terribly inconsistently but his high end stuff... actually suggest he could give Galactus a fight. In COIE I remember him taking it to the giant AM with asteroids.