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ReferencePerformance

Performance

Speed matters — every second of load time drops conversion by 5–10% on mobile. Citera is built lean to help.

What Citera does

  • Vanilla JavaScript, no framework. No React or Vue runtime to load.
  • No external font CDN. Fonts come from Shopify’s font library, served from Shopify’s edge — no extra DNS lookups.
  • No external script CDN. Theme scripts are hosted on Shopify’s CDN.
  • Lazy-loaded images. Images below the fold don’t download until the shopper scrolls near them.
  • Responsive image sizes. The theme serves the smallest image size that fits the shopper’s screen — no downloading a 4K image on a phone.
  • CSS is minimal. No CSS framework bloat.

What you should do

Compress images

Product photos should be 200–500KB each, not 5MB. Use tinypng.com  or Shopify’s built-in compression before upload.

Especially compress your hero image

The hero is the largest paint on the homepage — a heavy hero image sinks your Largest Contentful Paint (LCP) score.

Aim for hero images under 300KB. If you need a high-res look, upload multiple sizes and use Shopify’s responsive image serving to pick the right one.

Skip unnecessary apps

Every Shopify app that runs in the theme adds JavaScript and CSS. Common offenders:

  • Currency converters (Shopify Markets covers this natively)
  • Chat widgets (a big one — 200KB+ each)
  • Wishlist apps (unless you truly need it)
  • Announcement bars (Citera has one built in)

For each app in your store, check: does the value it provides outweigh the speed cost? Uninstall apps you don’t actively use.

Measure

Free tools:

  • PageSpeed Insights  — Google’s tool, shows LCP, INP, CLS scores
  • GTmetrix  — detailed waterfall of what’s loading
  • Chrome DevTools → Lighthouse — the same PSI in your browser

Test both your homepage and a product page. Mobile matters most.

Typical Citera scores

Out of the box, Citera scores in the 90+ range on PageSpeed Insights when:

  • Images are compressed
  • No heavy apps are installed
  • The store isn’t loading massive third-party scripts

If your score is below 60, the cause is almost always one of:

  1. Uncompressed images
  2. A heavy third-party app
  3. Marketing scripts (Google Tag Manager, Facebook Pixel — expected, but check how many)
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