When should you arrive at dfw in order to catch your flight?

2-3hours

That's base on your fly schedule and you should check in 3 hours before fly.

While DFW is a large airport they are extremely efficient I believe. An hour and a half to two hours is adequate from my experience.

Depends on how busy it is. I'd try to be there at least three hours before takeoff.

international 3 hours before

Two hours preview.