Mine was just having to continually render the objects. I set it up properly it would just drop my FPS with sphax which ironically I started using cause it gave me better fps. It was the reason I put my main sorting system underground in 1.4.7
I'm not trying to be a dick here when I say this but, that's silly. Just because you never experienced it doesn't mean those who did and have a working knowledge of the systems never had lag... a grand cause of the lag is the very same thing that allowed it to run, Timers. Having too many timers in one chunk was hell on the game.
I'd just quickly like to correct this: improperly setup pneumatic tube systems can cause tons of lag, exactly the same as BuildCraft pipes or Logistics Pipes. Setup a Pneumatic system PROPERLY and you'll never see lag.
That being said however.. Applied Energistics and Logistics Pipes really are the nail in the coffin for older systems like Pneumatic Tubes.
I'm not trying to be a dick here when I say this but, that's silly. Just because you never experienced it doesn't mean those who did and have a working knowledge of the systems never had lag... a grand cause of the lag is the very same thing that allowed it to run, Timers. Having too many timers in one chunk was hell on the game.