Where a server physically sits places a floor under response time that no amount of caching or code tuning can get beneath. It is worth understanding, because it is the one performance decision you make before writing any code.
The floor is physics
Light in optical fibre travels at roughly two-thirds of its speed in vacuum — about 200,000 km per second. Sydney to London is around 17,000 km, so a signal needs approximately 85 milliseconds each way, or 170ms for a round trip, in the theoretical best case. Real fibre routes are not great-circle lines and real paths traverse switches and routers, so the practical figure is higher.
That is not a tuning problem. It is a distance problem, and it is spent before your server has done anything at all.
Round trips multiply it
A page load is rarely one round trip. A fresh HTTPS connection needs a TCP handshake and a TLS handshake before the first byte of the actual request is sent, and each is a round trip of its own. A visitor on the other side of the world can therefore spend a substantial fraction of a second on negotiation before any HTML is generated.
This is why serving from a nearby region beats optimising the application for a distant visitor. You are removing round trips rather than shaving milliseconds off the work done between them.
What a CDN does, and what it does not
A CDN places static assets — images, stylesheets, scripts — near the visitor, and that genuinely helps. What it generally cannot cache is the HTML of a personalised or logged-in page, or any POST request. Those still travel to the origin.
So a CDN reduces how much of a page pays the distance cost. It does not remove that cost for the parts of a site that matter most, which are usually the checkout, the dashboard and the login.
Why three regions
We run our own hardware in our own racks in Sydney, Ashburn and London, serving Australia and APAC, North America, and the UK and EU respectively. Three is the smallest number of regions that places an origin within reasonable distance of most of the world’s traffic.
The interconnect is carrier-neutral — through NEXTDC, Megaport and the Sydney IX — which means routes into those regions do not depend on a single upstream provider.
Choosing yours
Pick the region nearest to most of your visitors, not the one nearest to you. If your customers are in the UK and you work from Melbourne, London is the right answer even though it makes your own admin marginally slower. You load the admin a few times a day; they load the site continuously.