There's a lot to consider when making a multiplayer game which requires frequent updates.
There's only so much data that can be sent in each message, so it sounds at a basic level like you've overloaded the update packet with too much info.
You'll run out of space anyway, so will need to think about interpolation to handle the "gaps" in the information.
You will want to plan out what exactly and how you will fill the info packets with. Probably want to pack integers with say 4 bytes of information, rather than one for instance.
Also, what / where is the server?
Is it peer-to-peer or dedicated?
Setting up a testing environment which allows you to test and verify throughput would be a good start. Joining, leaving, lobby, diagnostics etc. Probably don't even think about the actual game until the network code is developed.