Just wondering whether the 4200 EIO port can handle gigabit speeds? If so, is it a significant performance increase over 100 meg speeds and how does it compare with speeds printing over parallel?

The reason I want to know this is that I installed a 100 meg JetDirect card in a 4200 so that the printer could be used over a network by multiple users rather than just over parallel (one user). Now the primary user of the printer finds it prints quite slow compared to before.