Your Website Feels Fast to You. Here's Why Your Customers Disagree.
You open your website on the office MacBook. It renders in under a second. The images load cleanly, the menu appears, everything looks right. You make a mental note — fast — and move on.
Your customer, on her phone, on Verizon, in a Tampa Bay suburb, is having a different experience. She is still watching the page load.
These two experiences of the same website are not the same test. One of them is roughly representative of your business’s real-world performance. It is not the one you ran.
The 4.5× Speed Gap
Here is the concrete gap, sourced to 2024 and 2025 measurement data.
The US fixed broadband median download speed is 389.80 Mbps, according to the Ookla Speedtest Global Index. That is a figure from opt-in speed tests — users who deliberately ran a speed check — so it skews toward engaged users on good connections. It is a reasonable proxy for what your office WiFi delivers.
Your customer on Verizon mobile gets a different number. Ookla Speedtest Intelligence data for H2 2024 puts Verizon’s all-technology mobile median at 86.23 Mbps. That is not the headline 5G figure. It is the median across all of Verizon’s mobile traffic — 5G where available, LTE where 5G isn’t, and all the mixed-coverage conditions in between.
The gap: 389.80 Mbps on your desk versus 86.23 Mbps in a customer’s hand. That is a 4.5-times difference before you account for anything else — before cache, before device, before the specific way browsers handle page loads on a cellular connection.
For a business in a market like Tampa Bay, where customers are routing quote requests from job sites, parking lots, and neighborhoods with uneven 5G coverage, the median Verizon figure may be generous. A customer on AT&T’s all-technology median (95.08 Mbps, per the same Ookla H2 2024 report) is in similar territory. The gap between your testing environment and your customer’s device is structural and persistent.
The Real-World P75 Baseline
The Ookla figures above are still opt-in speed tests — users who opened a speed-check app and deliberately ran a measurement. People who do that tend to be on better connections and more engaged with their network than the average web user.
Alex Russell’s 2024 analysis of Cloudflare Radar data builds a more conservative and more realistic baseline: the 75th-percentile mobile user — meaning a quarter of your actual visitors are at this level or below — is on a connection delivering 7.2 Mbps down with a round-trip time of 94 milliseconds.
That is not a slow connection by historical standards. It is not a rural edge case. It is the P75 of actual populated, openly-connected countries with 50 million or more internet users — what a substantial portion of real visitors genuinely experience when they load a webpage on a phone.
Compared against your office broadband, 7.2 Mbps is 54 times slower. Compared against the Verizon median, it is 12 times slower. This is not a worst-case scenario crafted to make a point. It is the empirically derived browsing baseline for roughly one in four visitors to any web page.
The Three Illusions Your Own Testing Creates
When you check your site at your desk, three things are working in your favor that have nothing to do with how well the site is built.
The warm cache. Browsers store files from sites you’ve visited recently. When you open your own website for the second or tenth time this week, the browser retrieves many assets from local storage instead of downloading them again. The page “loads” in under a second because most of it never traveled the network. Your customer, arriving for the first time, gets a cold cache — every file downloaded from scratch, in sequence. The first-time experience can be substantially slower than what you see on your third visit this week.
Your device tier. A modern MacBook or flagship iPhone processes JavaScript faster than the mid-tier Android phone that a majority of mobile web users carry. JavaScript on a web page is not just downloaded — it is parsed and executed by the device’s processor. A script that takes 50 milliseconds to run on your laptop can take 300 milliseconds on a mid-range Android device. The script is identical. The execution time is not.
Your connection type. Office WiFi to a fiber or cable connection has low latency — typically in the single-digit milliseconds for round-trip communication. Mobile cellular has structural latency that does not disappear even on fast 5G. Ookla’s global data for 2024 puts global average mobile latency at 27 milliseconds; fixed broadband averages 9 milliseconds. That 3x latency gap compounds on every resource a browser must fetch: DNS lookup, security certificate negotiation, each file request. A page that requires 20 network round trips adds 540 milliseconds of latency overhead on mobile that simply does not exist on your office WiFi.
The result: your self-test is systematically optimistic on all three dimensions simultaneously. It is not measuring your site’s performance. It is measuring your site’s performance for you, under conditions that no prospect will replicate.
What It Means to Load in 3 Seconds on a Real Phone
Alex Russell’s 2024 analysis produces a specific and useful budget figure: to load interactively in 3 seconds on a P75 mobile device and P75 network connection, a JavaScript-heavy site must stay under 730 kilobytes total — with no more than 365 kilobytes of JavaScript specifically.
Most SMB websites built on WordPress, Wix, or similar platforms with accumulated plugins, booking widgets, live chat tools, analytics scripts, and third-party review embeds exceed this budget without anyone noticing. Each plugin is small in isolation. Collectively, they exceed the 3-second budget on a phone that half your visitors are using.
The page weight problem compounds because, as the HTTP Archive Web Almanac 2024 documented, page weight continued to grow through 2024 at roughly the same rate year on year. The pages are getting heavier. The devices carrying them are not proportionally faster. The performance inequality gap between high-end and low-end devices is, by the Web Almanac 2024’s account, widening — explicitly citing Russell’s research series.
The Worked Arithmetic
Consider a hypothetical home services business in Tampa Bay: 30 inbound quote requests per month from organic search. If only one in four mobile visitors — the P75 baseline, not an edge case — experiences a page slow enough to drive a back-click, and if those visitors were inquiring at even a 20% rate, the company loses 1.5 inquiries per month to speed alone. At a $400 average job value, that is $600 per month. Over a year: $7,200, from a problem the owner was unaware of because their own site felt fast.
The inputs are illustrative. The P75 baseline — 7.2 Mbps, 94 ms RTT — comes from Alex Russell’s 2024 Cloudflare Radar analysis. The job value and inquiry rate are chosen at plausible SMB scale for illustration. The point is the structure: speed problems that are invisible to the owner are not invisible to the visitors who experience them.
The “My Site Passed Google’s Speed Test” Objection
Many business owners who have checked their performance have used Google’s Lighthouse tool or PageSpeed Insights. These produce a score from 0 to 100 and a set of diagnostics.
Lighthouse is a lab test. It simulates a page load under controlled conditions — a specific simulated device configuration and throttled network speed, run at a single point in time. It is useful for identifying specific code problems. It does not measure what your actual visitors experienced.
The real-user measurement is CrUX — the Chrome User Experience Report — which captures actual load metrics from real Chrome users on real devices and real connections. Google uses CrUX field data for the Core Web Vitals classifications that affect your search standing. A Lighthouse score of 90 and failing CrUX field data for LCP (Largest Contentful Paint — time to biggest visible element), INP (Interaction to Next Paint — how fast the page responds to taps), or CLS (Cumulative Layout Shift — how much the page jumps around as it loads) are not contradictory. They measure different things. The CrUX data is the one that counts.
The gap between a favorable Lighthouse score and a failing CrUX reading is common and well-documented. A good Lighthouse score is not evidence that your customers are getting a fast page.
The Point About 5G
Faster carrier networks help. 5G pages load 21 to 26 percent faster than 4G pages for major services, per Ookla’s Q1 2024 research. That is a real gain.
It is not a sufficient fix. 5G improves bandwidth. It does not reduce the browser’s main-thread execution time for JavaScript — on a mid-range Android, often the actual bottleneck. It does not eliminate cellular latency: 47 milliseconds median on 5G versus 9 milliseconds on fixed broadband, per Ookla’s H2 2024 US data. The fix is the website, not the network.
How to See What Your Customers Actually See
A free performance assessment from iServU pulls your CrUX field data — what real Chrome users on real devices and real connections experienced when they loaded your site. It maps those real-user measurements against Google’s published performance thresholds and shows you where you stand.
You will see the LCP, INP, and CLS your actual visitors experienced — not the numbers your MacBook produced on a warm cache.
Gabriel Lopez-Seco runs it directly. No account manager, no handoffs.
Schedule a free assessment at iServU.
Sources
- Ookla Speedtest Global Index (2026). US fixed broadband median download speed. speedtest.net
- Ookla Speedtest Intelligence H2 2024 (2025). US mobile median download speeds by carrier — T-Mobile 5G: 281.52 Mbps; AT&T all-tech: 95.08 Mbps; Verizon all-tech: 86.23 Mbps; T-Mobile latency: 49 ms. ookla.com
- Russell, A. / Infrequently Noted (2024). The Performance Inequality Gap, 2024. Cloudflare Radar P75 network baseline — 7.2 Mbps down, 94 ms RTT; 730 KB / 365 KB JS budget for 3-second interactive load. infrequently.org
- Ookla (2024). 5G Page Load Speed, Q1 2024. 5G vs 4G load time improvements; global average mobile latency 27 ms vs fixed broadband 9 ms. ookla.com
- HTTP Archive / Web Almanac (2024). Performance Chapter and Page Weight Chapter — page weight trend growth, performance inequality gap. httparchive.org
