performance-optimization

Performance Optimization

Apply these performance optimization principles when developing web applications, themes, and frontend interfaces.

Core Performance Principles

• Prioritize server-side rendering as a first principle, as opposed to client-side JavaScript
• Minimize client-side JavaScript to reduce bundle size and improve Time to Interactive
• Optimize for Core Web Vitals: LCP, FID, and CLS
• Measure performance continuously and establish baselines
• Consider performance impact of every architectural decision

Server-Side Rendering

• Render content server-side whenever possible
• Use streaming rendering for faster Time to First Byte
• Implement proper caching strategies for rendered content
• Avoid blocking resources that delay rendering
• Pre-render static content where applicable

CSS Best Practices

Selector Efficiency

• Avoid ID selectors for styling; use classes instead
• Maintain specificity at 0 1 0 where possible
• Avoid deep nesting of selectors (max 3 levels)
• Use BEM or similar naming conventions for clarity
• Prefer class selectors over element selectors

CSS Organization

• Use CSS variables for colors, spacing, and repeated values
• Group related styles logically
• Remove unused CSS to reduce payload
• Consider critical CSS inlining for above-the-fold content
• Use CSS containment for complex layouts

Layout Performance

• Avoid layout thrashing (forced synchronous layouts)
• Use transform and opacity for animations (GPU accelerated)
• Minimize paint and composite operations
• Use will-change sparingly and intentionally
• Prefer flexbox and grid over floats and positioning

JavaScript Optimization

Code Organization

• Use the module pattern for code organization
• Prefix private methods with appropriate indicators
• Prefer const over let; avoid var
• Avoid external dependencies when native APIs suffice
• Split code into logical, loadable chunks

Loading Strategies

• Defer non-critical JavaScript
• Use async loading for independent scripts
• Implement code splitting for large applications
• Lazy load components and routes
• Preload critical resources