HTML Optimization & Core Web Vitals
Accelerate your webpage delivery and eliminate layout instability automatically. fast.site performs real-time edge transformations on your HTML markup.
Core Web Vitals Impact
Google uses Core Web Vitals to measure real-world page experience. fast.site improves the parts it can reach at the edge, before the HTML gets to the visitor's browser:
What are Core Web Vitals?
Core Web Vitals are Google's standardized metrics for measuring real-world web user experience. They evaluate three critical dimensions: how fast primary content loads (LCP), whether elements jump or shift unexpectedly while loading (CLS), and how quickly text and interactive elements appear on screen (FCP/INP).
Largest Contentful Paint (LCP)
Automatically detects your hero/primary above-the-fold image and injects a high-priority <link rel='preload'> tag to speed up main image rendering.
Cumulative Layout Shift (CLS)
Calculates image aspect ratios and reserves layout dimensions (width & height attributes) to prevent visual jumps while assets load.
Font Display Swap (FCP)
Injects font-display: swap into external web fonts to eliminate Flash of Invisible Text (FOIT), displaying text immediately to visitors.
How to Enable HTML Optimization
Turn on HTML Optimization for your domain in three easy steps:
Open Your Domain
Log in to the fast.site dashboard and select your domain from the domain list.
Navigate to Optimization
Click on 'Optimization' in the left domain sidebar (under the Speed & Performance category).
Toggle HTML Optimization
Flip the 'HTML Optimization' switch to Active. Changes take effect across our global edge instantly.
Platform Operations Gate
Platform administrators maintain an operational kill-switch (html.opt.enabled). If temporarily paused for maintenance, your preferences remain saved and resume automatically.