Ah, forgot to calculate the default TCP windows for you link speed rather than mine. So that's 125000000 bytes/sec ( 1 gigabit / sec ) * 25 milliseconds or 3125000 (for read) * 40 milliseconds or 5000000 (for write) net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.ipv4.tcp_wmem = 4096 3125000 16777216 net.ipv4.tcp_rmem = 4096 5000000 16777216 The 25 and 40 milliseconds are my guess at roughly the faster and more middle ping times within the domestic US Internet. This just gets each connection started net.ipv4.tcp_moderate_rcvbuf = 1 net.ipv4.tcp_timestamps = 1 cause the IP stack to very quickly establish precise values for the transmit and receive TCP windows.