I don't think it was ever the POBs themselves that caused the lag; I'm pretty sure it was the insane fleets that showed up to kill them that did.
EDIT: unless something changed since POBs were first introduced; I haven't played in... wow, almost two years.
Once upon a midnight dreary, while I pron surfed, weak and weary, over many a strange and spurious site of 'hot xxx galore'. While I clicked my fav'rite bookmark, suddenly there came a warning, and my heart was filled with mourning, mouring for my dear amour, " 'Tis not possible!", I muttered, "Give me back my free hardcore!" ... quoth the server, 404.
I thought we already knew PoB's didn't cause lagg. When DPC were going around hacking and destroying them and they were turned off and the server was just as laggy as it was before.