A new add-on is out: Fast Blocks.
It stops the storefront from building blocks it is not going to show.
What it does
• Blocks hidden on a device are no longer built for that device: no queries, no HTML, no cache entry. It reuses the visibility checkboxes you already set in the layout editor, so there is nothing new to configure. • Heavy blocks below the first screen leave the first response and load as the visitor scrolls to them, behind a skeleton that repeats the shape of what is coming.
Measured on a demo storefront home page
• device visibility alone: 371 KB → 275 KB on a phone • with lazy blocks: 373 KB → 186 KB on desktop, 360 KB → 170 KB on a phone
It is becoming part of our themes
Fast Blocks will ship with the ThemeHills themes. Thin is ready today: its layouts already carry the lazy markup, so a fresh install of the theme plus the add-on gets a light home page without touching a single setting.
What it refuses to do
Main content, product filters, breadcrumbs, the cart and every checkout step are never deferred. Those block types get no checkbox at all, so a wrong click cannot break a listing or an order.
Worth knowing before you switch it on: the device is part of the block cache key, and the storefront sends Vary: User-Agent. If Varnish or Cloudflare sits in front of the store, add the device to the cache key, the documentation shows how. And remember Google indexes mobile-first: hide decorative blocks on phones, not the text you want found.
CS-Cart and Multi-Vendor 4.11.1+, tested on 4.20. No template edits, nothing to compile. Admin interface in 30 languages.
Launch price: 51% off until 13 August 2026
Marketplace: Fast Blocks: device-aware and lazy blocks for CS-Cart
Demo: Shopping Cart Software & Ecommerce Software Solutions by CS-Cart