Most lag removed from the MPHX multiplayer library.
At github, mphx is a multiplayer library for haxeflixel. At that homepage the library is said to have lag issues. I removed most lag. The lag was created from the example file called movement . Now there is only a slight delay between moving the player and that same player moving at the other client. The library can be downloaded from my fork . Copy the downloaded mphx folder to the root of your project. The updated example file is here. At the example file, I also added onConnectionClose, disconnect event and function setExitHandler which will disconnect a player from other clients when that player closes the program.
The example file was tested with 4 open clients. Note that a fair amount of lag still exists with tcp. Udp is therefore the default. You can change back to tcp at mphx\client\impl\TcpClient.hx.
Alternatively, you can use Node.js sockets and play around there which has no lag from my experience.