[Captain_McCusker]

If your FPS drops low enough it's like having an incredibly high ping, you start to lag. Well, sorta. What's actually happening is your computer is trying really hard to keep up the calculations it needs to make for every sprite on the screen, and this includes those being transmitted by the server. Whereas a high ping just means that you're not transmitting the data back and forth to the server fast enough. In either case you're likely to lose enough data to make it very hard to play effectively.