Concerning a Hauppauge WinTV PVR-150 Media Center

I bought this card a while ago and originally wanted to just use it for TV. The TV was great, but I then was curious about running my Gamecube through it via composite connection.

The problem:
-User input has a great lag. For example, in Metroid Prime, I would move the joystick in any direction and I would not see a move on the screen for about 5 seconds. I experience this with all games.

The Question:
-Is that just the way things are, or is there anything I can do to create a lagless, or close to lagless, gaming environment using the TV tuner card?

Thanks!