Trail starts at around 6500' in elevation and is fairly easy walking. Eventually getting steeper with switchbacks and altitude starts to affect you. It doesn't help to rest. Keep moving even at a slow pace. A steady pace will get you to the top in about 3-4 hours. If you dawdle it will take you longer.
My druthers is to park a vehicle at the base of Sandia Tram, drive a second vehicle to the La Luz Trailhead, walk up, have lunch at the top and ride the tram down. I would rather climb than descend.
I have walked it in 2.5 hours but generally runs closer to 3-3.5 hours. First time I did it I didn't know what to expect and it took about 5 hours but it is more mental than physical. Once you know what to expect and try it you set a benchmark for yourself and try improving from there.
As you get a mile or so from the top you run into tourists who start at the top, wander down the trail for a mile or less then turn back to the top. Same at the bottom. Many start the trail, go up a couple of miles and then turn back. which leaves about 5 miles of trail with not much foot traffic.
Make sure and take plenty of water (I like a full camelback with 1.5 liters of water)