It adds tens of milliseconds to just downloading on a fast connection, plus it has to be parsed before what ever you need it to do will be functional.

To compare, just roughly:

For roughly the same size you can get declarative/reactive rendering with React, or an optimized FP standard library with ClojureScript, or data driven visualizations with d3 (roughly 2x the size).

For a tenth of the size you can get stuff like htmx, or a json validation library (avj), or like someone said Preact (React alternative).

But for jQuery, you're paying that for basically nothing the browser APIs don't already provide. It was a godsend 10y ago, but with legacy browsers finally fading out, the last one being ie11, you really don't _need_ it anymore.

30kb gzipped is still 10x larger than Preact for reference

that doesn't make it an issue in any way, it's not a numbers competition unless you have a 56K

One of the explicit goals of gov.uk is to be maximally accessible, and that includes for people accessing the Internet on a potato or who have a metered connection.

or use https://axios-http.com/ for ajax stuff