www.zearn.org speed test — 20 Oct 2026
Measured from the wfix.shop server on 20 October 2026 at 13:46 UTC. Grade B (81/100), with the screenshots, the timings and the fixes that matter.
Where the first byte went
- DNS lookup 115 ms 24%
- TCP connect 103 ms 21%
- Server wait 265 ms 55%
Measured on the connection that fetched the HTML. Every other request on the page waits for the end of this bar before it can start.
How this page compares
Every report published here is in this comparison, so it is a reference population of pages tested from one server - not a benchmark of the whole web.
What these numbers mean
- The first byte arrived in 483 ms. That is workable, and the cheapest win left is caching or a warmer connection.
- The page transfers 593.9 KB over 26 request(s). Javascript files are 47% of it, so defer what is not needed for the first screen, and drop tags nobody uses.
- It runs over HTTP/3, so the assets share a connection instead of opening one each.
- 83% of the weight comes from other hosts (analytics, fonts, embeds), which also means their slow day becomes your slow day.
- The largest element painted at 1.26 s, inside the 2.5 s Google calls good.
- Layout stayed still (CLS 0.020), so nothing jumps under the reader's cursor.
- The main thread was blocked for 93 ms in total, which is not enough to feel.
Fix first: Server response time (TTFB) - Cut server think time: page cache, query indexes, fewer synchronous calls to third parties inside the request. Connection setup is distance, so a nearer region or a CDN edge helps instead.
Read on one shared server, not a visitor's phone: use it to compare pages against each other, not as a promise about every connection. We fix what these tests find.
Screenshot
What the page looks like
Loaded in headless Chromium on this server. Click an image to open it full size.
Browser render
The same URL loaded in a real browser, so these are the readings curl cannot produce. The grade above is still built from the server measurements.
Page weight by type
What the page is made of
Transfer size, compressed as sent. 26 request(s) in total, 593.9 KB across all of them.
Top issues
Server response time (TTFB)
high impactThe first byte arrived after 483 ms. Of that, 265 ms was the server thinking and 218 ms was connection setup. A first byte under 400 ms is what a visitor feels as instant.
Fix: Cut server think time: page cache, query indexes, fewer synchronous calls to third parties inside the request. Connection setup is distance, so a nearer region or a CDN edge helps instead.
Compress text responses
high impact1 text response(s) of 10 KB or more are sent uncompressed, and the document itself is compressed. That is 152.8 KB of compressible text.
Fix: Turn on brotli (preferred) or gzip for text/css, javascript and text/html in the web server. This is the cheapest win available on almost any site.
Render-blocking resources
high impact26 render-blocking resource(s) in the document head (6 script(s), 20 stylesheet(s)). The page cannot paint until each one arrives.
Fix: Add defer or async to scripts that do not change the first paint, inline the critical CSS, and load the rest with media="print" plus an onload swap.
TLS certificate validity
high impactThe certificate for www.zearn.org has 20 day(s) left.
Fix: Renew automatically (certbot with a working renewal timer) and alert on the certificate, not on the renew command, so a silent failure is caught weeks before a browser warning.
Cache static assets
medium impact25 asset(s) answer without a Cache-Control max-age, so browsers revalidate them on every visit.
Fix: Version filenames on change and serve them with a long max-age plus immutable. That is what makes a returning visitor fast.
Waterfall
Slowest requests
Each bar is one request's own response time, scaled to the slowest. Assets were fetched in parallel, so the bars overlap in real time rather than stacking. first party third party
| Request | Type | Status | Time | Size |
|---|---|---|---|---|
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardButton-Dq04PKQM.css 3rd party | css | 200 | 1.29 s | 1.5 KB |
| https://webassets.zearn.org/app_assets/general/fonts/fontawesome-pro-5.10.1-web/css/all.min.css?v=1792503975 3rd party | css | 200 | 1.27 s | 152.8 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/ButtonLikeLink-BrDikaMe.css 3rd party | css | 200 | 1.27 s | 1.6 KB |
| https://webassets.zearn.org/app_assets/tokens/digitalClock/digital_7_fonts.css 3rd party | css | 200 | 1.25 s | 255 B |
| https://webassets.zearn.org/app_assets/general/logos/touch_icons/touch-icon.png 3rd party | images | 200 | 1.24 s | 4.1 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/LatexUtil-Dc_UIbyu.css 3rd party | css | 200 | 1.24 s | 7.1 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/AppButton-i76wn2Vu.css 3rd party | css | 200 | 1.24 s | 512 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardLink-wVRMexXW.css 3rd party | css | 200 | 1.23 s | 2.0 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/landing_page-D0DYhvhC.css 3rd party | css | 200 | 1.23 s | 1.3 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/AppLink-DvYk0B6x.css 3rd party | css | 200 | 1.23 s | 335 B |
| https://webassets.zearn.org/assets/zearn_fav_new.png 3rd party | images | 200 | 1.23 s | 3.1 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/landing_page-B9bZZ5Qa.js 3rd party | javascript | 200 | 1.22 s | 2.9 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/AppIcon-yNO6P280.css 3rd party | css | 200 | 1.22 s | 78 B |
| https://d33atdio81inpg.cloudfront.net/assets/application-8e32c9cb0e616054c4114322fa9a9091ed4fd983f17dcf42fc38c1af5f539dad.css 3rd party | css | 200 | 1.22 s | 42.0 KB |
| https://d33atdio81inpg.cloudfront.net/assets/includes-3293b978584e46f38e08f8d207c743e1155c38504e9cf69a5a1d7490996686c6.js 3rd party | javascript | 200 | 1.21 s | 184.4 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/polyfills-bZpcvW2o.js 3rd party | javascript | 200 | 1.21 s | 45.3 KB |
| https://d33atdio81inpg.cloudfront.net/assets/application-7d33cb0d99c7ea8bce6f8926d516c68988295cd5712c0fb9b7c9f7d53e6d9dc0.js 3rd party | javascript | 200 | 1.21 s | 32.0 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/vendor-COIF4Yvw.js 3rd party | javascript | 200 | 1.21 s | 10.9 KB |
| https://d33atdio81inpg.cloudfront.net/vite/assets/lib-BG4j772Z.js 3rd party | javascript | 200 | 1.21 s | 812 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardFormField-Rvx-NaFC.css 3rd party | css | 200 | 1.21 s | 945 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardFormPasswordInput-CfjGbv6K.css 3rd party | css | 200 | 1.21 s | 517 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardForm-PhKg0fqH.css 3rd party | css | 200 | 1.21 s | 400 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardFormInput-Cqta8y-T.css 3rd party | css | 200 | 1.21 s | 396 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/StandardFormLocked-BW5vSRga.css 3rd party | css | 200 | 1.21 s | 394 B |
| https://d33atdio81inpg.cloudfront.net/vite/assets/AriaLiveLoadingAlert-CFcubP6x.css 3rd party | css | 200 | 1.21 s | 140 B |
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