[BillinghamJ]

Assuming the FE resources are already cached on the user's machine, with careful optimisation, doing all of the rendering/fetching on the FE over a single connection, and with everything parallelised, it definitely is possible to load a new page well under 100ms with the key content being displayed.

When taking that kind of approach, you don't have to wait for the slowest thing to come in - eg with a normal BE render, you might need to pull up the user's profile and settings, A/B testing flags, the current footer config or whatever.

eg if you're on the page for viewing a single ticket, you can request the ticket data immediately, and render it as soon as it's available - even if other parts of the page aren't finished yet. True it may be more like 200-300ms to have the entire thing be 100% complete, but all parts of the page are not of equal importance and holding up the main content while loading the rest isn't necessary.

If you are doing a full BE render, it's still totally possible to hit that 100ms mark, but indeed dramatically more difficult.