www.kcl.ac.uk speed test — 20 Oct 2026

What these numbers mean

• The first byte took 810 ms. Everything else waits for that number, so the server is where to start: caching, a slow query, or an overloaded host.
• The page transfers 842.2 KB over 26 request(s). Images files are 77% 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 2.08 s, inside the 2.5 s Google calls good.
• Layout stayed still (CLS 0.003), so nothing jumps under the reader's cursor.
• The main thread was blocked for 44 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.