DFW has so many checkpoints, that security lines are rarely long. I typically see 2 minutes or less midday, up to maybe 10-15 during the Monday morning peak. The airport is so spread out that saving 10 minutes in line by using a checkpoint in another terminal really won't save any time.

That said, there's a checkpoint in the middle of terminal D under the hotel. It's not adjacent to any ticket counters, so during the rare cases when lines are very long (e.g. Holiday weekends), that may be your best bet.