When All You Can Do Is All or Nothing, Do Nothing

Summary

30 March, 2026 When All You Can Do Is All or Nothing, Do Nothing Written by Harry Roberts on CSS Wizardry. Table of Contents Independent writing is brought to you via my wonderful Supporters. Tools and Context Dumb Design Systems fetchpriority=high The Browser Default Is Not Failure Missed Opportunities Are Safer Than Bad Optimisations Use Hints Where You Have Certainty Do Nothing, Deliberately I’ve been working a lot over the last few years on the idea of web performance for design systems. While a lot of my clients want me to start at the end and work back (we have a slow site, how can we make it faster?), particularly ambitious clients ask how can we bake web performance in from the start? This post comes from a specific bit of advice I gave a client recently. Their design system sits on top of a highly permissive CMS. Editors have a lot of freedom—which is great—but it means the system often does not know, or cannot tell, if a component will render above or below the fold, on or off screen, or whether it will appear once or many times on the page. This makes things like loading=lazy and fetchpriority=high awkward: if an image might be an LCP candidate, then loading=lazy is bad news; if several images might be LCP candidates, then fetchpriority=high on all of them is bad news, too—when everything is high priority, nothing is. And so my take is this: when all you can do is all or nothing, do nothing. Tools and Context loading=lazy only helps if you apply it to things the user does not yet need, but apply it to something needed immediately and you may have made the page worse. Similarly, fetchpriority=high only helps if you use it to identify one likely winner among a field of contenders: apply it to all contenders and you have not clarified anything, you’ve just added noise. These are not magic make it faster attributes, they are hints, and hints are only useful when they are specific and contextual. Dumb Design Systems A design system (or any system, really) shou...