Why your website should be under 14kB in size

Having a smaller website makes it load faster — that's not surprising.

What is surprising is that a 14kB page can load much faster than a 15kB page — maybe 612ms faster — while the difference between a 15kB and a 16kB page is trivial.

This is because of the TCP slow start algorithm. This article will cover what that is, how it works, and why you should care. But first we'll quickly go over some of the basics.

What is TCP? #

Transmission Control Protocol (TCP) is a way of using the Internet Protocol (IP) to send packets of data reliably — sometimes this is referred to as TCP/IP.

When a browser requests your website (or an image or a stylesheet) it makes that request using HTTP.

HTTP is built on top of TCP and a single HTTP request is usually made up of many TCP packets.

On its own IP is just a system for sending packets of data from one location on the internet to another. IP doesn't have a way of checking if a packet has successfully arrived at its destination.

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