Ever have someone complain that a site takes too long to load?

Sometimes the issue is with the fact that it's just too much data that the browser has to parse, but other times the server can slow to begin responding.

curl -sL -o /dev/null -w "Connect: %{time_connect} TTFB: %{time_starttransfer} Total time: %{time_total} \nBytes Downloaded: %{size_download} Bytes in Headers: %{size_header} Bytes Uploaded: %{size_upload} Bytes in Request: %{size_request}\n" https://example.com 

This shows how long the initial connection takes, how long before the first byte, and then how big the data returned by the server is.