Keep-Alive is an HTTP header message, which is also referred to as a persistent connection. It provides a way to send and receive multiple requests over a single TCP (Transmission Control Protocol) connection, rather than opening and closing additional TCP connections, which would require additional requests and responses from the browser and server, after the initial connection closes. The benefit of this feature is that it allows servers to send multiple files to browsers, which reduces latency, CPU usage, and overall network congestion, helping load web pages faster. Continually having to open connections causes performance issues. This feature is specific to the HTTP 1.0 protocol. Since the introduction of the HTTP 1.1 protocol in 1997, all connections are considered persistent, unless otherwise specified, and do not utilize the Keep-Alive message.
How Does Keep-Alive Affect Web Page Performance?
Lighthouse is an open-source tool that is used to run an audit against your web pages and provides scores and suggestions for improving page performance, accessibility, SEO, and more.
PageSpeed Insights is a tool created by Google that reports on the performance of a page on both mobile and desktop devices, and provides suggestions on how that page may be improved.