TesterAgentWebsite speed test for desktop and slow mobile
TesterAgent's speed test loads your pages in a real browser on desktop and on a throttled slow-4G mobile connection and measures Largest Contentful Paint (LCP), First Contentful Paint (FCP), Total Blocking Time (TBT), Cumulative Layout Shift (CLS), Time to First Byte (TTFB) and page weight. The free check tests 3 pages and, in the same report, also checks UX, translations and functions, with a fix for each issue. These are lab measurements; for real-user data from Chrome users, also look at Google PageSpeed Insights.
Website
We check 3 pages in a real browser: speed, UX/UI, translation, functions and hosting (no security scan without an account).
By running a check you agree to the Terms and the Acceptable Use Policy.
App (APK)
No account needed for one free check — a website or an app. The report link works for 7 days. Create a free account to keep every report. · See a sample report
The metrics
| Metric | What it measures | Good |
|---|---|---|
| LCP | When the biggest text block or image is shown | ≤ 2.5 s |
| CLS | How much the layout jumps while loading | ≤ 0.1 |
| INP | How fast the page reacts to taps and clicks (field data only; we measure TBT in the lab) | ≤ 200 ms |
| FCP | When the first text or image appears | ≤ 1.8 s |
| TTFB | Time until the server sends the first byte | ≤ 0.8 s |
| TBT | Main-thread blocking time in the lab | ≤ 200 ms |
Source: web.dev: Web Vitals
Why slow mobile matters
Many visitors in Laos and Thailand browse on mid-range phones over mobile data. A page that feels fast on office Wi-Fi can take several seconds on a slow 4G connection, so we always test a throttled phone profile as well as desktop.
Frequently asked questions
How is this different from PageSpeed Insights?
PageSpeed Insights tests one URL and shows real-user Chrome data when available. We test several pages in the lab and also check UX, translations and functions. See the comparison page.
Is the speed test free?
Yes, as part of the free check: 3 pages, no account, one check every 30 days.