It actually applies to both PC and non-PC matches and this is just my theory from what I've experienced personally from the behavior I had in game.

It's the sound!

It's something to do with the sounds that every deployed object makes. I know in EVE for a very long time, in order to reduce lag in large fleet fights everyone would always disable the sound to prevent the client from crashing. Apparently you have somehow recreated the same problem in DUST. Only we don't get the option to disable the sound.

I'll use drop uplinks for my example. If you put down one drop uplink, it makes that nice soothing "woom woom" noise if you are withing a certain proximity to it. Well if you put down another one, it also wants to make that same woom woom noise only now it's competing with the original uplink and they are BOTH making the noise and sometime they don't mesh together well. No multiply this by like 2 dozen separate instances of "woom woom" all within proximity of you. If you step outside the area where they make the noise, no lag... Renter the area, suddenly all kinds of lag! Kinda like how in beta when you went from outside a building to inside the building and the game would glitch as it loaded the stuff it needed for the inside of the building.

So if it is indeed the sound processing choking the hell out of everything because it's trying to make 2 dozen instances of all the noises simultaneously while still running everything else, then I have a possible idea on a solution. So instead of trying to make 2 dozen noises, just make ONE. Whenever you check for proximity to any equipment to make the "noise" instead of continuing to check for others and wasting processing to do it, just set a flag to only check when not within proximity of the original object making the noise and make only the one noise not 2 dozen. Then when you leave prox of first one or if it is destroyed, then go back to original check for proximity to equipment and if true make the ONE noise again. If none, then stop.

Seriously, I don't need to hear a cacophony of 2 dozen uplinks to know that they are there. Just make one woom woom noise and good to go.

Anyways, just a thought and hopefully it gives you guys something more to go on as to the possible cause of all the lag.