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Critical Resources and the First 14 KB (2022)
Do you really need to optimise as much of your critical page into the first 14 KB of your HTML for TCP reasons? Or does that not hold true in an HTTPS world?
Now networks are incredibly fast – pretty close to the speed of light actually – and it usually only takes 10s or 100s of milliseconds for those responses to travel back and forth between server and client. HTTPS requires two round trips to set up the TLS connection, assuming the most commonly used TLSv1.2 and no session resumption here, as shown in the following handshake diagram: After this we have a couple more TCP ACKs before we get to the first real HTTP message (1316) where we send the response headers (including the 200 status code shown in the screenshot).
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