It's actually not that kernel. It's the CentOS kernel, which is the RedHat kernel, which was based on a 2.6 kernel years ago, but has since had every single kernel change under the sun backported to it. It might as well be RedHat's version of 3.10. This is also why it's a bad idea to build any kernel patches on top of RedHat kernels: it has nothing to do with the vanilla trees.

In any case, it doesn't matter if it's a 50 year old kernel. If it speeds up connections per second, someone will put up a box on the frontend with it as the load balancer.