XBL Lags only on Halo 3?

[Kainan F]

I don't know why, but XBL only seems to lag when playing Halo 3, i'll play ANY other online game and it won't lag one bit.

My internet speed is -

Download 3,900 - 4,100 ( it varys )

Upload - 400

I have a D-Link router DIR-619
And a Speedstream 5360 Modem.

ANY Help would be useful.

Thanks.