Australian businesses are pouring record money into winning the click while the sale leaks out in the second the mobile page takes to load. Site speed is treated as a developer backlog item when it is a conversion decision marketers are quietly losing every day. The cheapest growth most businesses have available is not another ad dollar, it is a faster page.
You are not losing these customers to a competitor. You are losing them to your own load bar.
The Take: Australian businesses are spending more than ever to win the click and losing the sale in the second it takes the page to load. Slow mobile pages are not a technical problem for the developers to get to eventually. They are a commercial decision you are making by default, and the cheapest growth on your table is a faster page, not another ad dollar.
Why is site speed a marketing problem and not an engineering one?
A 0.1 second improvement in mobile load time lifted retail conversions by 8.4% and average order value by 9.2% in one of the largest speed studies ever run. Speed is revenue, measured to the millisecond.
Here is the split that costs Australian businesses real money. Marketing owns the budget that brings someone to the page. The page itself sits in a developer backlog, ranked below a login bug and a feature request from last quarter. So the money to win the visitor comes out of one budget and the reason the visitor leaves sits in another, and the two teams rarely meet in the middle.
Australia's internet advertising market is now past $18 billion a year, and it grew again in 2025. In the audits we run across Australian businesses, Conversion Efficiency is consistently one of the weakest of the six dimensions we score. Slow mobile experience is the most common cause. We have measured this market. The pattern holds. Businesses are getting sharper at buying attention and no sharper at holding it once it lands.
What actually happens in the load time?
Australians spent a record $82.6 billion online in 2025, up 14% on the previous year, according to Australia Post. The average online transaction has fallen to about $96 on the same report, roughly $10 lower than it was in 2020. Buyers are shopping more often and spending less each time, which means every visit is worth less and you need more of them to convert.
More than half of that traffic arrives on a phone, on a connection that is not always fast, from someone who is half-distracted and one back-swipe from gone. Every extra second is a small tax on a purchase the customer had already half-decided to make. Sit with that. You are not paying the tax at the till where you would notice it. You are paying it in the load bar, where it never shows up with a name.
The numbers, by vertical
Those figures come from Milliseconds Make Millions, a study by Deloitte and Google across 37 retail, travel, luxury and lead generation brand sites and roughly 30 million user sessions. Read the size of that improvement again. A tenth of a second. Not a redesign, not a rebrand, a tenth of a second off the load time.
The study ran on European and US brands, so treat it as international evidence rather than an Australian measurement. The mechanism does not change at the border. A phone is a phone and patience is patience.
The lift in retail conversions Deloitte and Google measured from a single 0.1 second improvement in mobile load time
Why does this keep getting ignored?
The reason this blind spot survives is that the page never sends a bill. A slow page does not invoice you. It shows up as a slightly worse conversion rate that gets blamed on the ad creative, the price, the season, anything with a name attached to it. The lost sales rarely announce themselves, so the page never gets fixed and the ad budget keeps climbing to make up the difference.
That is the trap. You spend more to bring more people to a page that converts fewer of them, and the maths quietly gets worse while every dashboard says you are busier than ever.
Speed is the one growth lever you already own, already paid for and keep leaving switched off.
What I would do about it
Start by measuring the page in money, not milliseconds. Pull your conversion rate split by device and put mobile next to desktop. The gap between them, on the same traffic and the same offer, is a fair estimate of what the mobile experience is costing you.
Then test the real thing. Open your own site on a mid-range phone on a normal mobile connection, not the office wifi and not the newest handset in the room. Time how long until you can actually tap something and buy.
Get one screen in front of marketing and the developers at the same time, with mobile load time and mobile conversion rate side by side. The argument about whose job this is tends to end the moment both numbers are in the same room.
Fix the cheap wins before the expensive ones. Oversized images, third-party scripts loading on every page and a tag manager stuffed with tags left unaudited for a year will get you most of the way. Treat every 0.1 second you claw back as a budget line, because that is exactly what it is.
A note on methodology. When we score a business across the six dimensions, Conversion Efficiency is read from live signals including mobile load performance, not from a survey. It is directional. The confidence depends on the data a business shares. We are not publishing counts while the benchmark set is rebuilt. You can see the method at how we score.
Here is my opinion, stated as opinion. The next dollar most Australian businesses spend on ads is worth less than the tenth of a second they could shave off their mobile page, and almost none of them have run the comparison to find out. Speed is not the exciting part of marketing. It is the cheap part, and cheap growth is still growth. If you want someone to find where your page is leaking money and build the commercial case to fix it, that is the work we do inside NR Studio.
Frequently asked questions
Does site speed really affect conversions or just bounce rate?
Both. The Deloitte and Google study measured higher conversions and higher average order value from faster mobile pages, not only lower bounce. Speed changes what people buy, not just whether they stay.
How fast does my mobile site need to be?
Fast enough that the gap between your mobile and desktop conversion rate closes. Chase the gap, not a universal target number. If mobile converts far worse than desktop on the same traffic, load time is a prime suspect.
Is this a job for marketing or for developers?
Both, together, which is the whole point. Developers make the page faster. Marketing owns the reason it matters and the budget that proves it. Put mobile load time and mobile conversion rate on one screen and it stops being a turf question.
Are these speed figures Australian?
The Deloitte and Google numbers come from European and US brand sites, so treat them as international evidence. The Australian spend figures from Australia Post are local. The mechanism, a slower page means fewer sales, does not change by country.