How do you stop saintsrow The third lagging when you play in on Steam My PC - AMD FX 6100 Black Edition - nVidia GeForce 550 TI - 4GB DDR3 1333mhz - 1TB Hard Drive

Try turning shadows down if you're doing single player.
If co-op lag, not much you can really do unless you live near the person and you both have good up/down speeds. Settings on low will help a TON.