Here’s something I hear all the time: “I ran my website through Google PageSpeed Insights and got a 73. My competitor has a 98. Am I losing sales because of this?”
Maybe. But probably not for the reason you think.
There’s a ton of confusion around website speed, PageSpeed scores, and Core Web Vitals. Some people obsess over getting a perfect 100/100 score. Others completely ignore performance. And most business owners aren’t sure where the truth lies or what actually matters for their bottom line.
Let’s cut through the noise with real data. I’m going to show you what we actually know about how page speed affects your business, where the point of diminishing returns kicks in, and when “good enough” is genuinely good enough.
First, Let’s Clear Up What We’re Actually Talking About
Before we dive into the impact data, you need to understand what these terms actually mean, because most people confuse them.
PageSpeed Insights Score (The 0-100 Number)
When you go to Google PageSpeed Insights and test your site, you get a score from 0 to 100. This is a lab score - meaning Google tests your site in a controlled environment with a specific device and internet speed, basically like a simulated test.
Here’s the thing most people don’t know: This score is not a ranking factor. Google does not use this 0-100 number to decide where you rank in search results. (Source: Google Search Central)
The score is useful as a diagnostic tool - it tells you where there might be problems. But obsessing over whether you have a 93 or a 100 is mostly pointless. Both are “good” scores (90-100 is the green zone), and the difference between them has minimal real-world impact.
Core Web Vitals (What Google Actually Uses)
Core Web Vitals are three specific metrics that measure real user experiences on your website. Unlike the PageSpeed score, these are based on field data - actual measurements from real people using Chrome browsers visiting your site over the past 28 days. (Source: web.dev)
The three metrics are:
LCP (Largest Contentful Paint) - How long it takes for the main content of your page to load. Think of it as “when does the page actually become useful to someone?” The target is 2.5 seconds or less.
INP (Interaction to Next Paint) - How quickly your page responds when someone clicks, taps, or types. This replaced FID (First Input Delay) in March 2024. The target is 200 milliseconds or less.
CLS (Cumulative Layout Shift) - How much your page jumps around while loading. You know that annoying thing where you’re about to click a button and the page shifts and you click the wrong thing? That’s what this measures. The target is 0.1 or less.
To “pass” Core Web Vitals, at least 75% of your real users need to experience “good” metrics for all three - it’s the 75th percentile, not an average or single test. (Source: Google Search Central)
The key difference: PageSpeed is a lab test with simulated conditions. Core Web Vitals measures what actually happens when customers visit your site with their old phones on spotty wifi. You can have a perfect 100 PageSpeed score and fail Core Web Vitals, or vice versa.
What the Data Actually Shows: Page Speed and Business Metrics
Alright, let’s get to the meat of it. What do we actually know about how page speed affects conversion rates, revenue, and SEO rankings?
The Impact on Conversion Rates (Well-Supported)
This is where we have the most solid data, and the impact is real.
The broad strokes: Research from Portent found that sites loading in 1 second convert 5 times better than sites loading in 10 seconds. More conservatively, their data shows sites loading in 1 second convert about 3 times better than sites loading in 5 seconds.
Every second counts: Multiple studies consistently find that each additional second of load time decreases conversion rates by roughly 4-7%. A SOASTA study (now part of Akamai) found that even a 100-millisecond delay can reduce conversion rates, with the impact varying by device - 2.4% on desktop, 7.1% on smartphones, and 3.8% on tablets in retail contexts.
The 3-second wall: This keeps coming up across studies. According to Google’s Think with Google research, 53% of mobile users will abandon a site if it takes more than 3 seconds to load.
Product pages are especially sensitive: For ecommerce, product pages with a 2-second LCP see 40-50% higher conversion rates compared to the same pages with a 4-5 second LCP.
Real-World Case Studies (Specific Numbers)
Here’s where it gets interesting. These are actual businesses that optimized their Core Web Vitals and measured the impact through controlled A/B testing:
Ray-Ban (Source: web.dev case study) improved their Core Web Vitals and saw mobile conversion rates on product pages increase by 101.47%. Desktop conversions increased by 156.16%.
Vodafone (Source: web.dev case study) improved their LCP by 31% through an A/B test and got 8% more sales, a 15% improvement in lead-to-visit rate, and an 11% improvement in cart-to-visit rate.
Redbus (an online bus booking platform) saw 80-100% improvement in mobile conversion rates after fixing Core Web Vitals issues.
Amazon famously found that every 100ms of delay cost them 1% in sales. Walmart found the inverse - every 100ms of improvement increased revenue by up to 1%.
iCook (Source: web.dev) improved CLS by 15% and saw 10% more ad revenue.
Now, here’s the important caveat: These businesses didn’t just tweak a setting to go from a PageSpeed score of 95 to 100. They made significant improvements, often going from “poor” or “needs improvement” to “good” on Core Web Vitals. They were fixing real problems that real users were experiencing.
The Impact on SEO Rankings (Confirmed But Nuanced)
Let’s be straight about this: Core Web Vitals are a ranking factor. Google has confirmed this. But they’re not the ranking factor people think they are.
Google’s official position: Core Web Vitals act as a “tie-breaker” when pages have similar content quality. If your page and a competitor’s page both thoroughly answer the user’s query with quality content, better Core Web Vitals can give you an edge.
But - and this is critical - content quality and relevance matter far more than performance. Google’s own documentation states: “The intent of the search query is still a very strong signal, so a slow page may still rank highly if it has great, relevant content.”
What the data shows: Industry research analyzing large samples of websites has found that sites passing all Core Web Vitals tend to see better user engagement metrics - but it’s unclear how much is direct ranking benefit versus better user experience leading to more engagement signals.
The reality: Many high-ranking sites fail Core Web Vitals. Many sites with perfect scores don’t rank well. If you have great content and fail Core Web Vitals, you’ll probably still rank - but you’re likely losing conversions and revenue from the traffic you do get.
The Impact on User Behavior (Clear and Measurable)
This is where the data is most consistent, from Google’s Think with Google research:
Bounce rates: When page load time goes from 1 second to 3 seconds, the probability of someone bouncing increases by 32%. At 5 seconds, it increases by 90%. At 10 seconds, it increases by 123%.
Pages per session and time on site: Better performance leads to more engaged visitors who stick around longer. Multiple case studies show bounce rate improvements of 30-50% after Core Web Vitals optimization.
Mobile abandonment: 47% of consumers expect a web page to load in 2 seconds or less. 40% will abandon a website that takes more than 3 seconds to load.
Industry Variance (It’s Not All Equal)
The impact of performance optimization varies significantly by industry. Research suggests travel and booking sites see the highest conversion lift from speed improvements, followed by general ecommerce, with luxury retail showing lower (but still meaningful) sensitivity.
This makes sense: someone booking a last-minute flight is in a hurry, while someone buying a $5,000 watch might be more willing to wait. The key takeaway is that every 100ms improvement matters, but the magnitude of impact depends on your specific vertical and customer expectations.
The Point of Diminishing Returns: 80 vs 95 vs 100
Here’s the question everyone really wants answered: When should you stop optimizing? At what point are you wasting time chasing improvements that don’t matter?
The Sweet Spot and ROI Reality
Based on research and expert consensus, a PageSpeed score of 90-95 is “good enough” for almost all businesses:
- 0-49 (Poor): Real problems affecting user experience - high effort, high reward to fix
- 50-89 (Needs Improvement): Room for meaningful gains - moderate effort, moderate reward
- 90-100 (Good): Optimal range - stop here unless you have unlimited resources
The reality of 95 vs 100: The difference has minimal real-world impact. You’re often chasing hundredths of a second or optimizing things that don’t affect actual users. Multiple performance experts confirm that going from 95 to 100 burns days of developer time that would deliver far more value spent on content, UX, or other business priorities.
What Actually Matters: Field Data Over Lab Scores
The PageSpeed score is a lab test. What matters is Core Web Vitals field data - real measurements from real users. You might have an 85 PageSpeed score but pass all Core Web Vitals with real users (good outcome), or a 100 PageSpeed score but fail Core Web Vitals because your site behaves differently in the real world.
Focus on these questions:
- Are at least 75% of your users experiencing “good” LCP, INP, and CLS?
- What do your actual conversion rates and bounce rates look like?
- How does your performance compare to direct competitors?
If you’re passing Core Web Vitals and conversions are solid, stop optimizing. The ROI of further work rarely justifies the effort.
One important caveat: If each conversion is worth thousands (B2B SaaS, high-ticket services, enterprise sales), the ROI threshold for additional performance work is higher than for low-margin businesses. Even small percentage gains in conversion can justify more investment when individual customer lifetime values are substantial.
Common Misconceptions Debunked
“I Need a 100/100 PageSpeed Score”
Reality: No. A score of 90-95 is excellent. Many high-converting sites score 85-95. Focus on passing Core Web Vitals with real user data, not perfect lab scores.
“PageSpeed Score = Google Ranking Factor”
Reality: The 0-100 score is not a ranking factor. Google uses Core Web Vitals field data as a minor tie-breaker. Content quality matters far more.
“Failing Core Web Vitals Means I Won’t Rank”
Reality: Many top-ranking sites fail Core Web Vitals. Poor performance hurts your conversion rate and user experience more than your SEO. You get traffic but lose sales.
“Lab Scores Predict Real User Experience”
Reality: Lab scores can be wildly inaccurate. A site scoring 100 might perform poorly for real users on old devices with slow connections. Always check Search Console field data.
“If I Pass Core Web Vitals, Conversions Will Skyrocket”
Reality: Performance is necessary but not sufficient. Think of it as removing friction, not creating success. You still need good content, product-market fit, and conversion optimization.
Mobile vs Desktop: Why Mobile Speed Matters More
If you’re prioritizing optimization effort, focus on mobile first. Mobile devices account for approximately 60% of all website traffic globally (with regional variations), and Google uses mobile-first indexing - meaning your mobile performance affects rankings for both mobile and desktop search.
Mobile users are less patient (as we saw, 53% abandon sites over 3 seconds) and face slower connections and less processing power than desktop users. Industry research shows mobile-optimized sites achieve significantly higher conversion rates than non-optimized ones.
The opportunity: Most sites under-optimize for mobile. Improving mobile performance can give you a significant competitive edge.
What You Should Actually Do Next
Enough theory. Here’s your practical, prioritized action plan based on where you are now:
Step 1: Know Where You Stand
Check your Core Web Vitals field data:
- Go to Google Search Console (free)
- Click “Core Web Vitals” in the left sidebar
- Look at your mobile and desktop reports
- See what percentage of URLs pass for LCP, INP, and CLS
This shows you what real users experience, not lab tests.
Run a PageSpeed Insights test:
- Go to https://pagespeed.web.dev/
- Test your most important pages (homepage, key product pages, key landing pages)
- Note the score, but focus more on the Core Web Vitals metrics and specific recommendations
Check your conversion data:
- If you have analytics set up, segment by page load time to see if slow pages convert worse
- Look at bounce rates for different pages
- Compare mobile vs desktop conversion rates
Step 2: Prioritize Based on Your Current State
Poor range (PageSpeed <50, failing Core Web Vitals): This is costing you real money - likely 20-50% of potential conversions. Quick wins: optimize/compress images, enable caching, minimize JavaScript/CSS, use a CDN, consider faster hosting. These basics can get you to “needs improvement” in days.
Needs Improvement (PageSpeed 50-89, some CWV issues): Focus on the biggest PageSpeed flags: fix CLS issues (images/ads without dimensions, web fonts), improve LCP (optimize your largest content element), reduce JavaScript execution time, lazy-load below-the-fold content. Going from 70 to 90 delivers measurable ROI.
Good range (PageSpeed 90+, passing Core Web Vitals): Congratulations - stop here. The difference between 90 and 100 won’t move business metrics. Invest your time in content quality, conversion optimization, product development, or customer acquisition instead.
Step 3: Set Realistic Targets
Most businesses: 90+ PageSpeed score, 75% of real users passing Core Web Vitals (LCP <2.5s, INP <200ms, CLS <0.1).
Competitive ecommerce: 95+ on key pages, 90% of users passing, focus on mobile.
Don’t chase: Perfect 100 scores, every PageSpeed recommendation, or lab scores over field data.
Step 4: Know When to Get Help
Consider bringing in a web performance specialist or fractional CTO if:
- Your monthly revenue exceeds $10,000 and you’re failing Core Web Vitals (the optimization ROI will likely exceed the cost)
- You’ve tried basic optimizations but still can’t get into the “good” range
- You’re in a competitive market where small advantages matter
- You’re planning a major site redesign (build performance in from the start)
- Your team doesn’t have the technical expertise to interpret PageSpeed recommendations
A good performance consultant can often achieve in days what might take your team weeks of trial and error.
Step 5: Monitor and Maintain
Performance isn’t a one-time fix. As you add features, content, and third-party scripts, performance can degrade.
Set up ongoing monitoring:
- Check Search Console’s Core Web Vitals report monthly
- Set up alerts for Core Web Vitals regressions (tools like DebugBear, SpeedCurve, or Google’s web.dev metrics can help)
- Re-test key pages quarterly
- Before adding new features or third-party scripts, test the performance impact
Red flags to watch for:
- Sudden drops in Core Web Vitals passing percentage
- New JavaScript libraries or tracking scripts (common culprits)
- Spikes in bounce rate or drops in conversion rate
- Major site redesigns or platform migrations
The Bottom Line
Website speed absolutely affects your business - the data is clear. Slow sites lose visitors, hurt conversions, and leave money on the table.
But speed is not a silver bullet. A fast site with a bad product, unclear value, or weak content won’t succeed. I’ve seen businesses obsess over milliseconds while ignoring fundamental problems with their offering.
Your priorities:
- Get into the “good” range (90+ PageSpeed, passing Core Web Vitals)
- Optimize mobile performance
- Monitor and maintain over time
- Only chase perfect scores if you’ve nailed everything else
Performance optimization is a business investment that needs measurable returns. Spending days to go from 60 to 90 delivers ROI. Spending weeks to go from 95 to 100 rarely does.
The real goal isn’t a perfect score - it’s removing friction so people can get value from your site quickly. Sometimes that means optimizing performance. Sometimes it means clearer copy, simpler navigation, or better products.
Make performance good enough not to hurt you. Then focus on building something people actually want.
Need help optimizing your site’s performance or figuring out if it’s worth the investment? I work with early-stage companies and SMBs to make practical, data-driven decisions about infrastructure and performance. Get in touch if you want a straightforward assessment of where you actually stand and what’s worth fixing.