Setting a performance budget for a marketing website

Sites are rarely slow on launch day. They become slow over the following year, as tracking scripts, chat widgets, embedded videos and untouched hero images accumulate.

Agree the numbers up front

A workable budget for a marketing site: under one megabyte of transferred data on a typical page, largest contentful paint under two and a half seconds on a mid-range phone, and no more than three third-party scripts. Writing these down makes later requests a conversation about trade-offs instead of a default yes.

Protect the budget after launch

Check the numbers whenever something new is added. If a new tag pushes a page over the limit, something else has to go or the tag has to be loaded differently. A budget nobody reviews is just a paragraph in a proposal.