Comment by confusedcitizen

No no, I think he speaks of 50 requests from the get go, i.e., 50 requests of 100 friends each, irrespective of the number of servers. These 50 requests is unrelated to the number of friends, it's just some huge number of requests. He claims that no matter how you divide the data, if a certain number of requests create a CPU bottleneck, they'll continue to do so no matter how you increase memory.