Best low latency (<2-3 seconds) streaming service/program?

I'm not going to be doing any lets plays or anything, me and my friend just want to see each others screens (we both have a second monitor) while playing a coop/multiplayer game. Twitch, Steam, and YouTube are much too long, so I'm looking for something shorter. We both have 50 mbps internet so wifi speed shouldn't be too much of a problem.

tl;dr this service needs to be

1. under 3 seconds latency (1 would ideal)

2. 2 way

3. free, or close to free

Any solutions? Thanks!