Large bandwidth requirements
My initial testing had left me hopeful that the bandwidth requirements isn't that crazy for Second Monitor but after some testing on a server with other drivers connected I've come to the conclusion that I won't be able to use the application. While having someone monitor on my local network is fine, I'm overloading my 1Mbit/s upload link (yes I'm in a 3rd world country and still on ADSL).
A quick look at the message standard you're using and I'm noticing there isn't really much done to compress the information. There are some obvious bandwidth hogs like sending full driver names with every message instead of only sending it once with some ID and then tying the data back to the ID synchronised earlier. Then there's also a case to be made for some level of delta compression and quantization. These are items that could hopefully have a big impact on payload sizes and that could then have a positive impact on drivers trying to use the app with a spotter that might not be on their local network.
I've cloned the repository and will be poking and prodding around in it to try and better understand what's going on after which I'll hopefully be able to implement one or two of the items mentioned above, but if it somehow makes it into the app before I find the time to do so this will definitely become the tool of choice for me on race-day.