The gun feat where Superman was calculating in the femptoseconds.
Superman also has a feat where he traces a light signal that was moving in a matrix style path in a machine. That's better than nanosecond reactions.
Superman has another feat where he casually walks around and has a long conversation, loosens his tie, etc all inside the fraction of a nanosecond.
Carver, rather than asking him to show you it is easier to just Google it. Some years back I would have said check the issue (it is a relatively recent feat from Rebirth Supes), but I know that unfortunately less and less of the posters here actually READ comics ...hence my suggestion to ‘Google it.’
Superman has had (stated, not just inferred) femto reactions for a while now.
As for the Flash - above you claimed he was amped. I do not understand why you always try to lowball DC characters (actually I do - we all do), but after a while it really gets tiring.
There are some posters who are clearly trolls (and do an amazing job at it ...modern art level), and there are others who simply do not know better (and are likely children with character fetishes, which is also ok). You are neither, which is why it is so confusing. I don’t think you’re a troll, but you’re also not in the ‘child’ category.
Anyway - Superman has femto reactions. That doesn’t make him number one in speed in any category, but he does have femto reactions.