Have you ever benchmarked a server in the lab and then deployed it for real traffic, only to find that it can’t achieve anything close to the benchmark performance? CPU utilization is low and there are plenty of free resources, yet clients complain of slow response times, and you can’t figure out how to get better utilization from the server. What you’re observing is one effect of what we can call
![HTTP Keepalive Connections and Web Performance](https://cdn-ak-scissors.b.st-hatena.com/image/square/0ceb003f5a45cf8c2383163dc2b9948b891e1fcd/height=288;version=1;width=512/https%3A%2F%2Fwww.f5.com%2Fcompany%2Fblog%2Fnginx%2Fhttp-keepalives-and-web-performance.socialImage.png)