You have to reboot your game completely when that starts to happen. It's a memory leak issue, the more people and action around you, the more likely you are going to get DC'd and have to reboot.
Certain areas on the map are a problem as well. Most notable are the Crater, Iron Demon, Muir, and certain Arkfall locations in Sausalito, can be a problem if you have been connected long enough.
Playing on PS3 can be frustrating

. You can manage it somewhat, but it requires a lot of rebooting, I usually have to reboot the game every 2 hours, sometimes sooner, if I notice more lag.