I'm not sure how you are updating your info, but one thing that might help is to do a "SendtoOthers" call versus a "SendtoAll". If one client has already moved and you just need to send that status to the other client (but don't need extra network traffic) you can do a:
# this send to all clients but yourself
def SendToOthers(self, data, player):
for p in self.players:
if p != player:
You call it like(within a Python class):
From a Python script within Construct...I'm not positive how it would be called without some testing (not sure if it is a number or Class instance address). You can look at the Dungeon Server example from the tut for this.
Not sure though that will solve the problem. Perhaps it is just too much data to be sent during one tick. The myserver calls are asynchronous to Construct events....so Construct isn't going to wait for one call to finish before it does the next action. So Construct is going to loop through all the Units very rapidly firing off a myserver.SendToAll calls almost all at the same time..which might be creating a bottleneck. So maybe there is a way to experiment with breaking up not sending as much data each time or adding a slight pause (Wait plugin?..not sure how buggy it is) after each SendToAll in the "For Each Units" loop. How many units do you have?
As far as a limit: You shouldn't be trying to send more than 1500 bytes at a time (the Maximum Transmission Unit (MTU) over most networks. Although, I would suspect PodSixNet would handle that transparently, but I didn't check.
Give the above a thought and let me know how it goes.