The lead will help with lag, and enable you to send the signal to a better option than tiny telly speakers. It won't help with the buzzing as that is emanating from the guitar. When you say it starts buzzing as soon as Rocksmith has loaded a song, all that is telling you is that RS has selected a particular "tone" for that song. Depending on how high-gain that tone is will reflect upon how much buzzing you get. If you're playing a metal-type song then expect ultra high-gain plus loads of buzzing. As stated earlier, the buzzing diminishes as the quality of the guitar rises. Plus, chuck in single-coil or humbuckers into the mix. That's why I suggested maybe seeing if you could try another guitar, to put your mind at rest. And then there are good leads and bad leads too, lol.