Quality Score directly affects your CPC. A score of 10 cuts CPC by 50%. A score of 1 inflates it by 400%. Landing page speed is one-third of that score.
Key Takeaway
- Google Ads Quality Score of 10 earns a 50% CPC discount. A score of 1 inflates CPC by 400% (Adalysis practitioner research).
- Landing page experience contributes approximately one-third of Quality Score. Page speed is a primary factor in that assessment (Google Ads documentation).
- A 0.1-second improvement in load time increases retail conversions by 8.4% and lead generation conversions by 8.3% (Deloitte/Google, 37 brand sites).
- We tested 5 Australian sites running Google Ads. Lighthouse mobile scores ranged from 37 to 100. Three of five had Largest Contentful Paint over 8 seconds.
- A slow landing page costs you twice: higher CPC from reduced Quality Score, and fewer conversions from impatient visitors.
Every month, Australian businesses spend millions on Google Ads driving traffic to landing pages that load in 4, 6, or 8 seconds on mobile. They blame rising CPCs on competition. They test new ad copy. They adjust bids. They rarely check whether their landing page is the problem.
This report explains the mechanism connecting website speed to Google Ads cost, quantifies the impact with real data, and shows what it costs in extra ad spend.
How Quality Score works
Google assigns a Quality Score from 1 to 10 to each keyword in your search campaigns. This score directly determines how much you pay per click and where your ad appears.
The formula is straightforward: Ad Rank = Max CPC Bid x Quality Score x Expected Impact of Ad Extensions.
A higher Quality Score means you can maintain the same ad position while paying less per click. Or, at the same bid, you appear higher on the page. The score is calculated from three components:
| Component | Estimated weight | What it measures |
|---|---|---|
| Expected click-through rate | ~39% | How likely users are to click your ad |
| Landing page experience | ~39% | Speed, relevance, and usability after the click |
| Ad relevance | ~22% | How well your ad matches the search intent |
Source: Component weights from Adalysis practitioner research, derived from reverse-engineering historical auction data. Google does not publish exact weights.
Landing page experience is not a minor factor. It carries roughly equal weight to expected click-through rate. And unlike CTR (which depends partly on market factors), landing page experience is entirely within your control.
The speed-to-CPC relationship
Quality Score's impact on CPC is neither linear nor symmetrical. The penalties for low scores are steeper than the rewards for high scores. Quality Score 5 is the baseline, the neutral point.
| Quality Score | CPC impact vs. baseline (QS 5) | Example: if baseline CPC is $5.00 |
|---|---|---|
| 1 | +400% | $25.00 |
| 2 | +150% | $12.50 |
| 3 | +67% | $8.35 |
| 4 | +25% | $6.25 |
| 5 | Baseline | $5.00 |
| 6 | -17% | $4.15 |
| 7 | -29% | $3.55 |
| 8 | -37% | $3.15 |
| 9 | -44% | $2.80 |
| 10 | -50% | $2.50 |
Source: Adalysis practitioner research via Lionelz, directional estimates based on historical auction data
The average Quality Score across 15,666 Google Ads accounts is 5 to 6, according to WordStream's 2025 account study. Professional services tend to score lower: attorneys average 5.02, dentists 4.84. A score of 7 puts you ahead of most advertisers in almost every industry.
What this means in dollars
Consider a business spending $10,000 per month on Google Ads with an average Quality Score of 4. At QS 4, they are paying a 25% premium over the baseline. If they improved to QS 7 (a -29% discount), the same traffic would cost roughly $5,760, saving $4,240 per month, or $50,880 per year.
That is not hypothetical. One agency documented a 46% CPC reduction and 65% conversion increase after improving page speed and Quality Score by 3 points. Another saw a 37% CPC reduction and 42% conversion rate increase after rebuilding campaign landing pages to achieve 90+ Lighthouse scores on mobile.
The double cost of a slow landing page
A slow page hurts your Google Ads performance in two distinct ways, and they compound.
1. Higher CPC from reduced Quality Score
Google evaluates landing page speed through Core Web Vitals metrics and real-user data from the Chrome User Experience Report. A landing page that fails CWV on mobile signals poor user experience, which drags down the landing page experience component, which reduces Quality Score, which increases CPC.
Google's own documentation confirms: "In retail, we see that for every one second delay in page load time, conversions can fall by up to 20 percent."
Landing page experience improvements from "Below Average" to "Above Average" can reduce CPC by 16 to 50% and improve ad positions at the same bid.
2. Fewer conversions from the traffic you are paying for
Even if Quality Score were not a factor, a slow page loses visitors. Google's research found that 53% of mobile visitors abandon a site that takes more than 3 seconds to load. The bounce rate escalation is steep:
- 1 to 3 seconds: bounce probability increases 32%
- 1 to 5 seconds: bounce probability increases 90%
- 1 to 10 seconds: bounce probability increases 123%
Every bounced visitor is a paid click wasted. If your CPC is $5 and 50% of mobile visitors bounce because the page takes 6 seconds to load, half your ad spend is going straight to waste.
Portent's analysis of 100 million page views found that B2B sites loading in 1 second convert at 3 times the rate of sites loading in 5 seconds. For Google Ads traffic, where you pay for every single click, this conversion gap translates directly to cost per acquisition.
The evidence: speed improvements and business results
Three landmark studies quantify the relationship between speed and revenue.
Deloitte/Google: Milliseconds Make Millions
The Deloitte Milliseconds Make Millions study analysed 37 brand websites across retail, travel, and lead generation, covering over 30 million user sessions. Findings:
- 0.1-second improvement in load time increased retail conversions by 8.4%
- 0.1-second improvement increased lead generation conversions by 8.3%
- 0.1-second improvement increased travel page views by 9.2%
These are not large changes in speed. 0.1 seconds. The study demonstrated that even marginal speed improvements produce measurable revenue impact.
Rakuten 24: +53% revenue per visitor
Rakuten 24 invested in Core Web Vitals optimisation and measured the results: revenue per visitor increased by 53.37% and conversion rate improved by 33.13%. The improvements came from optimising LCP, CLS, and implementing modern loading patterns.
Vodafone: +8% sales from LCP improvement
Vodafone's case study documented that a 31% improvement in Largest Contentful Paint led to 8% more sales, a 15% improvement in lead-to-visit rate, and an 11% improvement in cart-to-visit rate.
These are publicly documented, source-linked studies from Google's own web.dev platform. They are not marketing claims.
What Australian landing pages actually look like
We tested 5 Australian websites that run Google Ads using Google PageSpeed Insights on mobile. These are real sites, tested in March 2026.
| Site | Lighthouse performance (mobile) | LCP | TBT | CLS | CrUX overall |
|---|---|---|---|---|---|
| Jim's Mowing | 100 | 1,726ms | 0ms | 0.01 | Fast |
| Hipages | 51 | 8,627ms | 297ms | 0.00 | Fast |
| Lawpath | 48 | 17,432ms | 648ms | 0.00 | Slow |
| CompareTV | 46 | 8,086ms | 378ms | 0.16 | Slow |
| Canstar | 37 | 8,381ms | 2,095ms | 0.00 | Slow |
Source: Google PageSpeed Insights, tested March 2026, mobile strategy
Jim's Mowing scores a perfect 100 with an LCP of 1.7 seconds. Every other site in the sample has an LCP over 8 seconds on mobile. Three of the five have an overall CrUX rating of "Slow," meaning real users consistently experience poor performance.
These sites are spending money on Google Ads to drive traffic to pages that take 8 to 17 seconds to render their main content on mobile. Based on Google's bounce rate data, more than half of mobile visitors are likely leaving before the page finishes loading.
The cost calculation
Consider a hypothetical scenario based on the data above. A site with Lighthouse 37 and LCP over 8 seconds is almost certainly receiving a "Below Average" landing page experience rating from Google, pushing Quality Score down by 1 to 3 points.
If they are spending $15,000 per month with an average Quality Score of 4 (25% premium over baseline), and a competitor with a fast landing page achieves Quality Score 7 (-29% discount), the cost difference is:
- Slow site CPC: $6.25 (at QS 4)
- Fast site CPC: $3.55 (at QS 7)
- Difference: $2.70 per click, or 43% more per click
At $15,000 monthly spend, that is roughly $6,450 per month in excess cost, or $77,400 per year. And that is before accounting for the lost conversions from visitors who bounce because the page is slow.
What is your landing page costing you?
We build landing pages that score 90+ on Google Lighthouse. Faster pages mean lower CPC, more conversions, and better return on ad spend.
See Google Ads management servicesHow to check your landing page speed
You can test your own landing pages in under a minute.
1. Google PageSpeed Insights. Go to pagespeed.web.dev, enter your landing page URL, and run the test on mobile. Look at the Lighthouse performance score (aim for 90+) and the Core Web Vitals assessment (aim for all green).
2. Google Ads Landing Pages report. In your Google Ads account, navigate to the Landing Pages report. Google shows the mobile speed score and landing page experience rating for each page receiving ad traffic.
3. CrUX Dashboard. The Chrome User Experience Report provides real-user performance data from actual Chrome users visiting your site. This is the same data Google uses to evaluate landing page experience.
The metrics that matter most for Google Ads:
| Metric | Target | Why it matters |
|---|---|---|
| Largest Contentful Paint (LCP) | Under 2.5 seconds | How fast the main content appears. Primary speed signal. |
| Interaction to Next Paint (INP) | Under 200ms | How fast the page responds to user interaction. |
| Cumulative Layout Shift (CLS) | Under 0.1 | How much the page content shifts while loading. |
| Total Blocking Time (TBT) | Under 200ms | How long JavaScript blocks the main thread. |
What to fix first
Not all speed optimisations deliver equal impact. Based on the data, here is what moves the needle most for Google Ads landing pages.
1. Fix LCP (this is usually the biggest problem)
LCP measures how quickly the main content appears. It is the metric most strongly correlated with landing page experience ratings. Common LCP killers:
- Unoptimised images. Large JPEG or PNG hero images are the most common cause of slow LCP. Convert to WebP, compress, and set proper width/height attributes.
- Render-blocking resources. CSS and JavaScript that load before the main content can be parsed. Move non-critical CSS to async loading and defer non-essential JavaScript.
- Slow server response. If Time to First Byte is over 600ms, the page is slow before any content loads. Use a CDN, implement caching, or consider edge rendering.
2. Reduce JavaScript payload
Heavy JavaScript is the second most common issue. Every kilobyte of JavaScript must be downloaded, parsed, and executed. On mid-tier mobile devices, this creates noticeable delays.
Google's data shows the median WordPress page ships 528 KB of JavaScript. Pages with chat widgets, heatmaps, A/B testing tools, and multiple tracking scripts can exceed 1 MB. Each script adds latency.
Audit your landing page scripts. Remove anything that does not directly contribute to conversion. Analytics and essential tracking can stay. Everything else should be evaluated against its performance cost.
3. Eliminate layout shift
CLS (Cumulative Layout Shift) measures how much the page content moves after initial render. Elements that load late and push other content around create a jarring experience. Common causes include images without dimensions, dynamically injected ads, and web fonts that swap with visible text.
This matters for Google Ads because layout shift during form interaction can cause users to click the wrong element or lose their place, increasing bounce rates and reducing conversions.
The technology gap
The underlying technology of your landing page affects how difficult it is to achieve strong performance.
Only 43.44% of WordPress sites pass Core Web Vitals on mobile, according to Google's CrUX data. WordPress sites built with Elementor drop to 26.99%. The median WordPress mobile Lighthouse score is 38.
Modern frameworks like Next.js achieve near-perfect scores by pre-rendering pages at build time and serving static HTML from edge networks. The page loads before the server even needs to do work. For Google Ads landing pages, where every millisecond affects CPC and conversion rates, this architectural advantage translates directly to lower advertising costs.
This does not mean you need to rebuild your entire website. Even within WordPress, targeted optimisations (image compression, script reduction, caching, CDN) can meaningfully improve landing page speed. But the starting point matters, and the data shows that some platforms make speed significantly harder to achieve.
Methodology
Landing page speed tests were conducted using Google PageSpeed Insights via the PageSpeed Insights API in March 2026. All tests used the mobile device strategy. Each site was tested once. Results include both Lighthouse lab scores (simulated mid-tier mobile device on 4G connection) and CrUX field data (real Chrome user measurements at the origin level).
Sites were selected based on visible Google Ads activity in Australian search results for common commercial queries. The sample is not comprehensive or randomised. It illustrates the range of landing page performance among advertisers, not a statistical population mean.
Quality Score CPC impact data comes from Adalysis practitioner research, which reverse-engineered historical auction data to estimate the relationship between Quality Score and actual CPC. These are directional estimates, not exact figures published by Google.
How Much Does Google Ads Cost in Australia?
Complete breakdown of Google Ads pricing in Australia, including industry benchmarks, management fees, and what to budget.
Read moreSources
- Google Ads: About Quality Score - Official Quality Score documentation
- Google Ads: About Ad Quality - How Google determines ad quality
- Google Ads: Speed Matters for Ad Experiences - Google on landing page speed and conversions
- Adalysis / Lionelz: Quality Score CPC Impact - QS 1-10 CPC multiplier estimates, component weights
- WordStream: Quality Score Account Study 2025 - Average QS of 5-6 across 15,666 accounts
- Deloitte/Google: Milliseconds Make Millions - 0.1s improvement = 8.4% more retail conversions
- Rakuten 24: Core Web Vitals Investment - +53.37% revenue per visitor from CWV optimisation
- Vodafone: LCP Improvement - 31% LCP improvement = 8% more sales
- Google/SOASTA: Mobile Speed Benchmarks - 53% mobile abandonment at 3+ seconds
- Portent: Site Speed and Revenue - B2B sites at 1s convert 3x rate of 5s sites
- Benly: Google Ads Landing Page Optimisation - Landing page experience CPC impact
- Digital Agency Net: Page Speed and Google Ads - Case study benchmarks
- CrUX Technology Report - CMS Core Web Vitals pass rates
- HTTP Archive Web Almanac 2024 CMS Chapter - WordPress median Lighthouse score
Frequently Asked Questions
Does website speed affect Google Ads cost?
Yes. Landing page experience is one of three components of Google Ads Quality Score, contributing approximately one-third of the overall score. A slow landing page reduces Quality Score, which directly increases your cost per click. Industry research estimates that a Quality Score of 1 costs 400% more per click than the baseline score of 5, while a score of 10 earns a 50% discount.
What is a good landing page speed for Google Ads?
Aim for an LCP (Largest Contentful Paint) under 2.5 seconds on mobile. Google evaluates your landing page speed through Core Web Vitals metrics. Google's own research found that every one second delay in page load time can reduce conversions by up to 20% in retail. Most Google Ads clicks now come from mobile devices, so mobile speed is what matters.
How does Quality Score affect CPC in Google Ads?
Quality Score acts as a multiplier in the Ad Rank formula. At Quality Score 5 (the baseline), you pay the standard rate. At Quality Score 10, you earn up to a 50% CPC discount. At Quality Score 1, you pay up to 400% more. A business spending $10,000 per month with an average Quality Score of 4 could be paying $2,500 to $5,000 more per month than a competitor with Quality Score 7.
What are the three components of Google Ads Quality Score?
Quality Score is calculated from three factors: expected click-through rate (approximately 39% weight), landing page experience (approximately 39% weight), and ad relevance (approximately 22% weight). Landing page experience evaluates page speed, mobile-friendliness, content relevance, and ease of navigation. Adalysis research estimated these weights from reverse-engineering historical auction data.
How much can I save by improving my landing page speed?
The savings depend on your ad spend and current Quality Score. As an example, a business spending $10,000 per month that improves Quality Score from 5 to 8 through better landing page experience could save approximately $2,900 per month, or $34,800 per year. Vodafone found that a 31% improvement in LCP increased sales by 8%. The Deloitte/Google study found 0.1 seconds of improvement increased conversions by 8.4%.
