In Kunming? I find that hard to believe, given the fact that 1 hour is the standard for every airport I've used in China apart from PEK T-3 (because it is massive). ETA: chinatravelguide claims 30 minutes is the proper number for international departures from KMG.

Regarding traffic, according to wiki, KMG is a mere 4 km south of "metropolitan Kunming". Since I've never been there (yet) --I'm unable to verify this claim-- but, if it's remotely close to accurate, even Bangkok style traffic wouldn't be much of an issue. Furthermore, only the ride into town would take place during rush hour. I'd be willing to bet that Kunming's roads are not teaming with cars at 10p.