> There are also security issues: if you're referencing some JavaScript from a CDN, you're trusting the people running the CDN to actually serve the JavaScript you request.
In the HTTP/2 world, it will likely be better to not do this.
The old tricks of relying on it being in browser cache already doesn't forego the fact that the connection to the server is expensive and HTTP/2 gives you a nice open connection to your server already... I would bet that a site is faster by taking as many third-party or other domain assets and putting them back on the same domain and same server.
In the HTTP/2 world, it will likely be better to not do this.
The old tricks of relying on it being in browser cache already doesn't forego the fact that the connection to the server is expensive and HTTP/2 gives you a nice open connection to your server already... I would bet that a site is faster by taking as many third-party or other domain assets and putting them back on the same domain and same server.