Interesting post, thanks for sharing!

About the suggested sysctl.conf settings: I think you'd also need to adjust net.core.rmem_max and net.core.wmem_max in order for the net.ipv4.tcp_rmem and net.ipv4.tcp_wmem settings to be effective.

Furthermore it couldn't hurt to increase net.core.netdev_max_backlog, which is the maximum number of packets queued on the input side, when the interface receives packets faster than kernel can process them.