Each terminal in DFW is approximately 3000 feet to walk all the way around. Plus about 800 feet for the walkways between terminals. You're not going quite a whole terminal (by 9 gates, or a quarter of a terminal). So if it's about 3000 feet, and you walk at 264 feet/minute (3 miles an hour), it'll take you 11.36 minutes.

Skylink won't be much shorter, if any. You have to walk from C14 to C12, take it one stop, then walk from A29 to A23.