Rules
Animated Content
Checks for large GIFs that could be converted to video
Browser-Required Audits
Lists performance audits that require browser execution
Cache Headers
Checks Cache-Control header configuration
CLS Optimization Hints
Checks for Cumulative Layout Shift prevention
Compression
Checks for Gzip or Brotli compression
Critical Request Chains
Identifies chains of dependent resources that delay rendering
CSS File Size Too Large
Checks for CSS files that exceed recommended size limits
JavaScript File Size Too Large
Checks for JavaScript files that exceed recommended size limits
DOM Size
Detects excessive DOM complexity that impacts performance
Duplicate JavaScript
Detects duplicate JavaScript libraries loaded multiple times
Font Loading
Checks for font loading best practices
HTTP/2
Checks for HTTP/2 protocol support
INP Optimization Hints
Checks for Interaction to Next Paint optimization
JavaScript Redirects
Detects JavaScript resources that return 3XX redirects
JS Libraries
Detects JavaScript libraries and checks for known vulnerabilities
Lazy Loading Above Fold
Detects lazy loading on likely above-fold images
LCP Optimization Hints
Checks for Largest Contentful Paint optimization opportunities
Legacy JavaScript
Detects ES5 polyfills and legacy JavaScript code
Preconnect Hints
Checks for preconnect hints to critical third-party origins
Render-Blocking Resources
Checks for render-blocking CSS and JavaScript
Source Maps
Checks for source map availability and configuration
Time to First Byte
Measures server response time (TTFB)
Total Page Weight
Checks the total byte weight of the page
Unminified CSS
Detects unminified CSS that could be optimized
Unminified JavaScript
Detects unminified JavaScript that could be optimized
Disable All Performance Rules
squirrel.toml