system
Given the following post, respond as if you're commenting on Reddit:
human
[DCEU Movies] Just how fast is Superman?

I have went through so many forums from Google and I can't seem to find a definitive answer. All the answers are between Mach 7 and Mach 900. How fast is he?
gpt
Supes' travel speed, when he's really high in the atmosphere and when there's significantly less friction, is some big number, it's impossible to tell. 

For "combat speed" or what would be relevant to a fight, around the speed of sound, maybe a little more. You can frame calc how fast Supes moves in combat and it's not mach 5 fuckbillion or anything. Even Flash who moves around as fast as Supes if not faster usually acts within the 100 m/s-Mach range throughout Justice League.