The trans Tasman data path runs over a small number of undersea cables: the Tasman Global Access cable and the Southern Cross system are the two main routes. Both are publicly documented infrastructure. Theoretical fibre latency between Auckland and Sydney sits around 25 to 30 ms; in practice, mobile traffic typically pays an additional 30 to 80 ms because mobile carriers route through several internal hops before reaching the cable.
Source: Book the call; Wikipedia, Southern Cross Cable.
Why the impact lands harder on mobile than desktop
HTTPS handshakes negotiate over multiple round trips. Each round trip pays the latency above. On a fibre desktop connection in the CBD this is invisible. On a phone on regional 4G, where the underlying connection is already slower and the towers are further from the major exchanges, the extra round trips add up to a meaningfully slower page load.
Google has used Core Web Vitals as a ranking signal since June 2021 (the page experience update). The Largest Contentful Paint metric in particular is sensitive to first byte latency. A site that loads in two seconds in Auckland CBD on UFB might be loading in four seconds in Whangarei on 4G simply because the host is in Sydney.
Source: Google Search Central, Page Experience update details.
How to find out where your site is hosted
Use a free tool like whatsmydns.net or run a traceroute from your local terminal. If your DNS resolves to an IP block in AWS Sydney, Linode Sydney, or any of the major Australian hosting brands, you are almost certainly served from the Sydney availability zone.
NZ hosting options worth a look
- Sitehost, Auckland based, strong WordPress performance, NZ owned and supported.
- Voyager, points of presence in Auckland and Wellington, NZ owned.
- Cloudflare in front of an existing host, with NZ edge nodes serving cached content. Useful if you cannot move the origin host immediately.
Source: Cloudflare network map.
Migration is typically a one afternoon job for a small business site. Most NZ hosts will handle the move at no charge if you sign up.
If you want a free site speed audit including a hosting recommendation specific to where your customers actually use phones, the strategy call covers it.
Edited by a human.