[vanadium]

In my experience, the variety of specific versions of libraries sites are locked to dilutes that performance benefit. Just look at a cross-sampling of sites calling jQuery or <insert your favorite library or framework here>.

In theory, the maximum benefit of a CDN only comes if everyone is on 1) the same version or, similar but different, 2) an evergreen version. And the latter is a big red neon sign screaming "DANGER".

[tripzilch]

And the parts that everyone is on, became standardized in the browser: document.querySelector, CSS animations, async stuff, etc.