You have less than 1kb requests and less than 1kb responses on average.
Let's see how many requests a 1gb net card can do? Well it's bit's not bites, but it's also a full duplex so you have 1gbit up and download. 1gigabyte / (8 kiliobit) = 1,000,000 / 8 = 125,000 requests per second. Granted full TCP/IP has a fair amount of overhead, but if you use UDP you can get vary close to this.
Yet, they don't need to get anywhere near that performance, for every 100 million clients updating every four hours using a random second to connect is around 10k connections a second.
