Why speed is money
Every extra second of loading is minus 7–10% of conversion. Google and Yandex directly factor speed into ranking. And a mobile user on average 4G closes the tab if nothing appears within 3 seconds. So a slow site loses twice: both search traffic and those who did make it through.
How to measure, not guess
- PageSpeed Insights — the main tool. It shows a 0–100 score and specific problems. Look at the mobile version: it’s always worse, and it’s exactly what most visitors see.
- Core Web Vitals — three Google metrics: LCP (when the main content appeared, the norm is up to 2.5s), INP (response to a click, up to 200ms), CLS (does the layout jump, up to 0.1).
- The Network tab in the browser — shows exactly what loads slowly: a 4 MB image or the chat script.
Top causes of a slow site
1. Heavy images — culprit №1
A phone photo weighs 3–8 MB. On a site its place is 100–300 KB. What to do:
- Convert to WebP — 25–35% lighter than JPEG at the same quality. For old browsers keep a PNG/JPEG fallback via the
<picture>tag. - Serve a size to fit the screen: a phone doesn’t need a 2560px image.
- Enable lazy loading — images below the fold load only when you scroll to them.
2. Cheap or overloaded hosting
If the server responds in 1.5 seconds (TTFB), no image optimization will save you. The TTFB norm is up to 200–500 ms. Sometimes migrating from ₽150 shared hosting to a decent VPS speeds up the site twofold without a single line of code.
3. Third-party service scripts
An online chat, three analytics counters, a map widget, social-media pixels — each pulls hundreds of kilobytes. A review twice a year: what’s actually used? A map can be loaded on click, a chat — with a couple of seconds’ delay.
4. No caching
Without a cache the browser downloads everything anew on every visit, and the server builds the page from scratch. Enable browser caching (Cache-Control headers), server-side page caching, and for online stores — database query caching (e.g. Redis).
5. No compression and HTTP/2
Gzip or Brotli compress HTML/CSS/JS 3–5 times. HTTP/2 loads files in parallel. Both are enabled on the server in half an hour.
CDN: when it’s needed
A CDN serves static files from the server closest to the visitor. It’s needed if your audience is spread across the country or the world. If all clients are in one city and the server is in Moscow, the effect will be modest.
Where to start: a week’s plan
- Run the site through PageSpeed Insights, record the “before” numbers.
- Compress and convert images to WebP — usually gives the biggest gain.
- Enable compression, caching and HTTP/2 on the server.
- Remove unused scripts and widgets, load the rest deferred.
- Check TTFB — if over 500 ms, talk to your host or migrate.
- Measure “after” and enjoy.
Takeaway
Speeding up a site isn’t a one-off campaign but hygiene. But 80% of the result comes from four things: light images, decent hosting, a cache and a script review. Want it done for you — order a site audit: we’ll show the bottlenecks with numbers.
