Website Speed and Google Ads: What You Can Measure

Slow landing pages can waste paid traffic. Learn what Quality Score tells you, what speed tests cannot prove, and how to measure cost per qualified enquiry.

Key Takeaway

The displayed Quality Score is a diagnostic. Google says it is not an input in the ad auction.
Landing page quality matters to advertising performance, but a Lighthouse score does not reveal an account's CPC, Quality Score or lost revenue.
Measure page experience alongside completed, qualified enquiries or sales. A cheaper click is useful only if it brings the right customer.
Our historical five-site speed snapshot illustrates performance differences. It cannot establish advertising outcomes or a national benchmark.

A slow landing page can make it harder for someone to use a form, read an offer or buy after clicking an ad. Improving it is worth testing. The commercial question is whether the change produces more qualified enquiries or sales for the money spent.

Updated 27 September 2026: an earlier version treated the displayed Quality Score as an auction multiplier and used it to calculate fixed CPC discounts and savings. Those claims have been removed. They were not supported by Google's current documentation or by our speed-test data.

Quality Score and auction-time quality

Google's Quality Score documentation describes the keyword-level 1-to-10 score as a diagnostic. Its components are expected click-through rate, ad relevance and landing page experience. Their statuses help identify potential improvements; they do not assign page speed a fixed share of the score.

Ad Rank uses auction-time assessments alongside bids, thresholds, competition, search context and the expected impact of assets. Better quality can help costs and eligibility. The displayed Quality Score does not provide a formula for calculating CPC or a guaranteed discount.

What you can observe	What it helps you decide	What it cannot prove
Landing page experience status	Whether relevance and usability need investigation	That speed alone caused the rating
Lighthouse lab results	Which loading, scripting or layout problems to investigate	What every visitor experiences
CrUX field data	How eligible real Chrome visits perform over its reporting window	The performance of only your paid visitors
Spend and qualified conversions	Whether the campaign produces suitable enquiries at an acceptable cost	That a page change caused every difference

Historical Australian speed snapshot

The original March 2026 report recorded one mobile PageSpeed Insights test for each of five Australian websites selected after observing advertising activity. The table below preserves those reported lab results. It is not a fresh measurement or a test of their advertising accounts.

Site	Reported Lighthouse performance	Reported LCP	Reported TBT	Reported CLS
Jim's Mowing	100	1,726 ms	0 ms	0.01
Hipages	51	8,627 ms	297 ms	0.00
Lawpath	48	17,432 ms	648 ms	0.00
CompareTV	46	8,086 ms	378 ms	0.16
Canstar	37	8,381 ms	2,095 ms	0.00

Four of the five reported lab LCP results exceed eight seconds. That is a reason to investigate the tested pages, not evidence that these businesses overpaid for ads. A single simulated visit can differ from real-user field data.

Methodology and limitations

The original report describes PageSpeed Insights API tests using the mobile strategy, conducted once per site in March 2026. The sample was selected, small and not randomised. The exact tested URLs, timestamps and raw API responses are not included in this publication, so the table is not independently reproducible from the article alone. It should not be reused as a current ranking of these businesses.

We did not measure their bids, search terms, Quality Scores, paid-traffic conversion rates or revenue. We cannot infer those from speed scores. We have therefore removed the earlier estimates of excess annual ad spend and the implication that lab results prove a particular landing page experience rating.

A useful way to measure the cost

Use your own campaign and enquiry data. For an illustrative calculation, AUD $3,000 in media spend divided by 20 qualified enquiries is $150 per qualified enquiry. If the same spend produces 25 qualified enquiries, the figure is $120. Management and other costs would need to be added for a fully loaded acquisition cost.

That arithmetic is not a forecast of what a speed improvement will deliver. Changes in search demand, targeting, bids, ad copy and qualification can all change the result.

Record the landing page, device, campaign, spend and qualified conversions for a suitable baseline period.
Test the form, booking or purchase journey on mobile. Confirm that successful actions are tracked and that duplicate or spam enquiries are excluded from business reporting.
Use PageSpeed Insights to identify specific issues. Separate lab diagnostics from field measurements.
Improve the issues most likely to obstruct the visitor, such as a slow main image, heavy scripts or a form that shifts while loading.
Where traffic permits, compare variants with an experiment. Otherwise compare equivalent periods and record other changes; treat the result as observational.
Judge the outcome using qualified enquiry cost and sales quality, alongside performance measurements.

What to check on the page

Core Web Vitals measure loading, responsiveness and visual stability. The good thresholds are LCP at or below 2.5 seconds, INP at or below 200 milliseconds and CLS at or below 0.1, assessed at the 75th percentile. A passing result does not guarantee an advertising outcome.

Also check whether the page delivers what the ad promised, explains the offer, works on a small screen and makes the next step clear. A fast page with an irrelevant offer can still perform poorly. Choose a rebuild only when targeted repairs cannot reasonably meet the requirements; both WordPress and custom sites can have performance problems.

Check the page and the campaign together

We can review your landing page, conversion tracking and campaign scope, then recommend the work worth doing.

See Google Ads management

Google Ads costs and management fees in Australia

Separate media spend, management fees and landing-page work when setting your budget.

Sources

The Google Ads explanations were checked on 27 September 2026. The historical lab observations remain dated March 2026 and were not rerun for this correction.

Frequently Asked Questions

Does website speed affect Google Ads cost?

Speed affects the experience after an ad click and can affect whether visitors complete an enquiry or purchase. Google also considers landing page quality in Ad Rank. A speed test alone cannot establish the effect on cost per click or predict a saving. Measure actual campaign costs and qualified conversions.

What is a good landing page speed for Google Ads?

Google's good Core Web Vitals thresholds are LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less, assessed at the 75th percentile of real visits. These are user-experience thresholds, not a guarantee of lower advertising costs.

How does Quality Score affect CPC in Google Ads?

The displayed 1-to-10 Quality Score is a diagnostic and is not an input in the ad auction. Google assesses quality at auction time alongside bids, competition, context, thresholds and assets. Improving the underlying experience can help performance, but no fixed CPC discount follows from a particular displayed score.

What are the three components of Google Ads Quality Score?

Expected click-through rate, ad relevance and landing page experience. Use each component's status to identify what needs attention. The number of components does not mean page speed has a one-third weighting.

How much can I save by improving my landing page speed?

There is no reliable savings figure from a Lighthouse score alone. Compare ad spend and qualified enquiries before and after a change, or run a controlled landing-page test where traffic permits. Account for changes in bids, targeting, seasonality and lead quality.