Not really. The master server has to handle less than 30KB per second (180 servers, 100KB images each) due to preview images, and that's about it.
I excluded the forums because it's impossible for me to calculate that.
The ban-warning packets are probably sent compressed.
Imagine that ^ was a seperator parsed by the master server, and that the second 1 is a bit for BL_ID banning (0 would be IP banning)
Like: 7EB8^1^3F34^-1^Bye bye, and hope you stay permabanned!
That string sizes to about 50 bytes on ANSI coding, but the hex parts and the numbers would probably be raw hex.