reset your router/modem. BF3 is an absolute graphics beast that uses up a ton of processing power on the PS3 and multiplayer seems to tax my poor little modem to the max. Reseting it may help. That and ensuring your PS3 is upright and cool can help. It gets really hot running BF3 compared to other games. Clean out the vent ports. Try to determine if the stuttering is due to overheating of the GX graphics card in the PS3. That is the weak part in the design on the motherboard. Regular maintenance and replacing that shitty heat sink medium that Sony uses can help it run much smoother.