www.zotero.org speed test — 20 Oct 2026
Measured from the wfix.shop server on 20 October 2026 at 14:18 UTC. Grade A (90/100), with the screenshots, the timings and the fixes that matter.
Where the first byte went
- DNS lookup 57 ms 16%
- TCP connect 24 ms 7%
- Server wait 272 ms 77%
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 354 ms. That is workable, and the cheapest win left is caching or a warmer connection.
- The page transfers 870.8 KB over 16 request(s). Images files are 52% of it, so resize and recompress the largest images before anything else.
- The HTML itself arrives gzip-compressed.
- It runs over HTTP/3, so the assets share a connection instead of opening one each.
- The largest element painted at 572 ms, inside the 2.5 s Google calls good.
- The main thread was blocked for 45 ms in total, which is not enough to feel.
Fix first: Image delivery and format - Serve WebP or AVIF with a JPEG fallback, size images to the space they occupy, and lazy-load anything below the fold. Images are usually more than half of a slow page.
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. 16 request(s) in total, 870.8 KB across all of them.
Top issues
Image delivery and format
high impact1 image(s) over 200 KB and 1 large image(s) still served as JPEG or PNG.
Fix: Serve WebP or AVIF with a JPEG fallback, size images to the space they occupy, and lazy-load anything below the fold. Images are usually more than half of a slow page.
Cache static assets
medium impact12 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.
JavaScript weight
medium impact1 JavaScript file(s) over 200 KB: web-components.min.1782766472.js (297.6 KB)
Fix: Split routes, remove unused dependencies, and prefer a two-file build (one pinned library, one application bundle) over many small ones.
Avoid extra redirects
medium impact1 redirect hop(s) before the page load started, each one a full round trip before the first byte.
Fix: Link to the canonical URL (and make sure http, the apex domain and www all point at it) so no visitor pays a redirect first.
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://www.zotero.org/static/images/icons/mastodon-logo-white.svg | images | 200 | 607 ms | 1.1 KB |
| https://www.zotero.org/static/images/bs4theme/zotero-logo.1775160902.svg | images | 200 | 554 ms | 1.2 KB |
| https://www.zotero.org/static/images/home/cite.svg | images | 200 | 533 ms | 1.3 KB |
| https://www.zotero.org/static/fonts/36AC02_4_0.woff2 | fonts | 200 | 524 ms | 32.3 KB |
| https://www.zotero.org/static/images/home/sync-lg.svg | images | 200 | 524 ms | 1.2 KB |
| https://www.zotero.org/static/images/home/sync-md.svg | images | 200 | 523 ms | 1.2 KB |
| https://www.zotero.org/static/images/home/organize.svg | images | 200 | 522 ms | 3.2 KB |
| https://www.zotero.org/static/images/home/screenshot-7.0.png | images | 200 | 519 ms | 430.2 KB |
| https://www.zotero.org/static/fonts/36AC02_5_0.woff2 | fonts | 200 | 518 ms | 29.5 KB |
| https://www.zotero.org/static/js/bs4/web-components.min.1782766472.js | javascript | 200 | 512 ms | 297.6 KB |
| https://www.zotero.org/static/images/home/collaborate.svg | images | 200 | 499 ms | 7.5 KB |
| https://www.zotero.org/static/images/home/static-collect.svg | images | 200 | 497 ms | 6.6 KB |
| https://www.zotero.org/static/css/bs4/web-components.min.1782766476.css | css | 200 | 496 ms | 44.6 KB |
| https://www.zotero.org/static/images/home/sync-xl.svg | images | 200 | 496 ms | 1.2 KB |
| https://www.zotero.org/static/images/home/privacy.svg | images | 200 | 496 ms | 514 B |
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