preconnect tells the browser to open the DNS + TLS connection to an origin early, before it discovers a resource there. Used well it shaves hundreds of milliseconds off the first request to fonts, CDNs and analytics.
How to fix it
- Add
<link rel="preconnect">for the 2–4 most important cross-origin hosts (e.g.fonts.gstatic.com), withcrossoriginwhere credentials/fonts apply. - Remove preconnects to origins you don't use — each open connection has a cost and they compete with real requests.
- Keep the total small (≤ 5). Beyond that the hint dilutes itself.
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>