Okay, I made some changes to the networking code.

The following changes will appear in version 0.19:
Instead of everyone sending and receiving data about your location thousands of times per second, it now only sends data 12 times per second (once every 5 game frames). I have been watching the network activity on my home network and it's so low, it's showing no network usage at all.
There is a downside to this though:
Because we're not updating locations as often, movement for other players will appear jerkier.
The fix to this will be to write some "prediction" code. I could in theory estimate where the other players will be and just draw them in the new location, keeping the game looking smoother for the most part. This will take a long time to get working properly though and it's low priority since it's entirely for looks only.
Here's my plan:
That value of "5" (sending data every 5 frames) is very easily-changable.
In a version in the near future, I will let the host choose, in the options menu, the number of frames between network updates. This will players to reduce the value to zero or 1 for LAN games and to higher values for more stable performance over long distances. This will actually be simple to impliment, I could have it in for the next version.

Eventually we could even maybe use latency times to estimate an appropriate value so all this will be hands-off and reliable, no matter what, but I'll get back to you on that.
