One thing you can try is to have the sockets use smaller buffers. The default socket buffer size is typically 8 kBytes for receive and 8 kBytes for send. Set the reduce-socket-buffer-memory variable to yes if you would like the server to try to reduce memory usage. That is done using the SO_RCVBUF and SO_SNDBUF socket options, which may not be implemented, or worse, not implemented correctly. If you try this, be sure and test that the server still works with it on.
The best way of course, is to properly tune your kernel if you plan to run a high-volume server.
Examples: