In the 90s a friend of mine and I used to play Q1 with dial-up modems, and one had to call the other one, using a phone number, etc. How does that work today? Not the dial-up part, but hosting. That method was fine for us back then (didn't even have a 3d card), but now I want a good ping and no stuttering, etc., when playing. If we both got ezquake installed, could one host without problems, or do we need a server?

You don't need a server. Just have your friend connect to your ip-address once you have started playing.

How would that impact us (or me) performance-wise? Will it lag?

try it

It's just that I would like to know before I try to convince someone to download it.

you will have the best possible ping, your opponent will have whatever he pings to you, if you have the same ISP, it should be all fine.

Sounds good. Thank you.