It's not a "premature" optimization if you know you're going to need it at some point. The thing that makes an optimization premature is if you're not sure you

It's not a "premature" optimization if you know you're going to need it at some point. The thing that makes an optimization premature is if you're not sure you need it, but when it comes to networking you can generally calculate out pretty quickly how much data you're going to need to transfer and what latency you're going to need. There are a lot of optimizations that you KNOW you'll need in a game upfront, and it's easier if you get it in your architecture early. (For instance, spacial partitioning trees and sprite packing) Not to mention that, augmenting networking into a project later on is a tremendous pain. It's one of those things you have to build in from the start; so if you know you're going to need fast packet-based unreliable networking you'll save yourself a lot of pain by doing it from the start. Realistically though, you should just use a library for networking instead of writing it yourself, if you can.