Can't Set Google TV to Game Mode for AV Port; Extreme Lag

I recently purchased a new TV for gaming, a TCL 43Q51BG. However, the input lag with the AV port is extreme and unacceptable, and the "Game Mode" and "Game Master" settings are grayed out and unselectable. How do I put the TV into game mode? I also purchased an AV-to-HDMI adapter, but it did not work at all. I'm currently using the OEM AV adapter.