Website performance isn't a nice-to-have — it's a business imperative. Studies consistently show that every 100ms of latency costs measurable revenue. Amazon found that a 100ms delay reduced sales by 1%. Google confirmed that page speed is a direct ranking factor.
Why Performance Matters
User Experience
Users expect pages to load in under two seconds. Anything slower and bounce rates skyrocket. A fast website feels professional and trustworthy; a slow one feels broken.
SEO Impact
Google's Core Web Vitals — Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS) — directly influence search rankings. Sites that score well on these metrics gain a measurable edge in search results.
Conversion Rates
Walmart found that for every 1-second improvement in load time, conversions increased by 2%. Performance optimization is one of the highest-ROI investments you can make.
Core Web Vitals Explained
Largest Contentful Paint (LCP)
LCP measures how quickly the largest visible element loads — typically a hero image or heading. Target: under 2.5 seconds.
How to improve LCP:
- Optimize and compress images (use WebP/AVIF formats)
- Preload critical resources with ``
- Use a CDN to serve assets from edge locations near users
- Minimize render-blocking CSS and JavaScript
Interaction to Next Paint (INP)
INP measures responsiveness — how quickly your site reacts to user interactions like clicks and taps. Target: under 200ms.
How to improve INP:
- Break up long JavaScript tasks into smaller chunks
- Use `requestIdleCallback` for non-critical work
- Minimize main thread blocking
- Defer non-essential third-party scripts
Cumulative Layout Shift (CLS)
CLS measures visual stability — whether elements shift around as the page loads. Target: under 0.1.
How to improve CLS:
- Always set explicit width and height on images and videos
- Reserve space for dynamic content and ads
- Avoid injecting content above existing content
- Use CSS `contain` for layout isolation
Image Optimization
Images typically account for 50-70% of a page's total weight. Optimize them aggressively:
- Modern formats: Use WebP or AVIF instead of JPEG/PNG (30-50% smaller)
- Responsive images: Serve different sizes for different screen widths using `srcset`
- Lazy loading: Use `loading="lazy"` for images below the fold
- Compression: Use tools like Sharp, Squoosh, or TinyPNG to compress without visible quality loss
Caching Strategies
Effective caching can eliminate redundant network requests entirely:
- Browser caching: Set long `Cache-Control` headers for static assets
- CDN caching: Use services like Cloudflare or Vercel Edge Network to cache at the edge
- Service workers: Enable offline access and instant repeat visits
- Stale-while-revalidate: Serve cached content immediately while fetching fresh data in the background
JavaScript Performance
- Code splitting: Load only what's needed for the current page
- Tree shaking: Remove unused code at build time
- Dynamic imports: Load heavy modules on demand with `import()`
- Bundle analysis: Use tools like `@next/bundle-analyzer` to identify bloat
How We Optimize at RCB Software
Every project we ship targets a Lighthouse performance score of 95+. We achieve this through framework-level optimization with Next.js, automatic image optimization, edge caching on Vercel, and continuous performance monitoring. Performance isn't an afterthought — it's built into our process from day one.