At that rate, you are limited by context changes from userland to the OS. So you must use an event driven approach like nginx or node.js. In contrast to the Apache way of opening a thread per connection.

Also, make use of netmap: http://info.iet.unipi.it/~luigi/netmap/ That is available for FreeBSD and Linux.

10k messages per sec is doable. But probably not off the shelf.