I have HDMI and VGA on my laptop, which is better for gaming on a TV?

I have a Gateway T-16, it has both VGA and HDMI outputs to either a external monitor or TV, and when i had my laptop hooked up to my 32″ TV via HDMI last night, playing Flatout, it didnt matter what the screen configuration was, the game still lagged, and it never lags on my laptop. Is it because of the HDMI? would it perform better using VGA? or how about a VGA to composite converter?

I want to play my games on the big screen, but i want to play them without lag, how do i do it?

System specs:
-Windows 7 Home premium X86
-2GB ddr2 RAM
-1.90GHz dual core AMD Turion 64 X2
-ATI Radeon X1270

having the laptop plugged in didnt help much either.