The fact of the matter is that Doom even at that level doesn't have the reaction feats that would justify him being able to deal with someone who can process information on a femto-second level scale.
He would be assailed with hundreds of millions of punches that have broken the time stream before, all before a single synapse can fire.
Superman would actually have time to leave the fight, make love to Jimmy Olsen, write the daily planet's sports section, neuter Krypto, listen to Lois get raw dogged, and STILL have enough time to come back and continue his assault on Doom.
All before Doom can fantasize about being Reed Richards.