I'm connecting in DFW next week and was wondering if I was to go landside to meet up with someone, how long would it take to go back through security?

My flight from ORD gets in at 5:55PM.

It all depends on the terminal, time and length of line. Typically, lines there are not much more than 10 -15 minutes though

I'll be flying out of Terminal B, but arriving into A I think. I'll be changing Terminals anyway. There's about an hour between both flights.

Each terminal has multiple security entrances. If we find a long line at one we simply walk down to the next one where there is usually not a line. Taking a three minute walk can save us waiting 30 minutes in line.

However, don't assume that the terminals listed on your flight info now will still be the same on day of travel. They often change. On a flight last month I checked which terminal we'd be flying out of before I left home and double checked it by phone a few minutes before we arrived at the airport. By the time we got to the airport it had been changed to another gate in a different terminal.

If the person you're meeting has a membership to the Admiral's Club, he/she can call in advance (24 hours, or no later than Friday for Sunday admission) and request a security clearance for a meeting at the AC, even if they're not travelling. Thus, that person could enter past Security and you wouldn't have to.

My usual security time at DFW is about 5 minutes or less, maybe 10 on a Monday morning. It rarely gets longer than that except for holiday weekends. When you exit security, just have a quick look at the line to make sure it's not abnormally long.

BTW, there's very little outside security at DFW, in the way of bars, restaurants, or even comfy chairs. Consensus is, the best place for this sort of meet-up is the Hyatt hotel at Terminal D. Check the South forum for a recent thread on this topic.

It won't be necessary to leave the secured area to change terminals at DFW. The Skylink tram system connects them all and it is inside the so-called 'sterile area'.

Besides the previously mentioned lack of amenities outside security at DFW I would not recommend leaving the secured area because, with a one hour connection, once you subtract the time needed to get off your original flight and get to your new gate in time for boarding you'd only have a few minutes landside, not time for much beyond "Howdy, Tex" and "Goodbye, Tex". There are ways a non-passenger can get a pass to come inside security; frequently mentioned here are scheduling a meeting at an airline club like American Airlines' Admirals Club (You didn't say but if you're transiting from "A" to "B" you're almost certainly on AA) or having the person you're meeting purchase a fully refundable ticket for the day of your flight, then request a refund for it after getting through security.