The lag. Is it the game or my wlan connection?

I've noticed every now and again the in-game lag is real bad. I don't have much experience with these new games and HaG is the only game I'm playing at the moment. I was wondering if the lag (like playing with 1FPS) is a result of something to do with the game, or an issue with my wlan connection. Most of the time it's fine then some days it's a mess. My PC has pretty decent specs.

Thanks.