1.3 Multiplayer Low FPS

When I play in single player, I can run the game perfectly fine at 60 FPS, but when I go into multiplayer I drop all the way down to 10 FPS. I've tried reducing my resolution all the way down to 800x600, but it still is unplayable. The most I can do is turn off frameskipping, locking me at 30 FPS and causing huge lag issues. I have tried with 1.3.0.3, and the issue still remains. I run without backgrounds, low quality, multicore lighting off, and all.

1.3 Multiplayer Low FPS