Web Performance Checklist for 2026

Performance influences trust, conversion, and search visibility. This checklist helps teams prioritize the highest-impact improvements.

1. Media and asset delivery

• serve modern image formats where supported
• use responsive image sizes to avoid oversized payloads
• compress assets without visible quality loss
• lazy-load non-critical media below the fold

Goal: reduce initial payload and accelerate meaningful rendering.

2. JavaScript and main-thread pressure

• remove unused libraries and heavy dependencies
• defer non-critical scripts
• split bundles by route where possible
• minimize long tasks that block interaction

Goal: improve responsiveness and lower interaction delay.

3. CSS and render path

• keep critical styles lean
• avoid excessive unused utility output
• prevent layout shifts with explicit media dimensions
• reduce expensive animations on low-end devices

Goal: stable visual loading and smoother first interaction.

4. Caching and delivery infrastructure

• set strong cache headers for static resources
• use CDN edge delivery for global latency reduction
• version assets for safe long-term caching
• validate cache hit rate after deployments

Goal: faster repeat visits and lower server load.

5. Core Web Vitals workflow

Track and improve:

• Largest Contentful Paint for loading experience
• Cumulative Layout Shift for visual stability
• interaction responsiveness metrics for usability

Use both lab and real-user monitoring to catch regressions early.

6. Mobile-first QA protocol

Test on constrained devices and networks, not only desktop broadband.

Check:

• first render and first meaningful interaction
• form usability under slower conditions
• sticky elements and overlays performance
• visual stability during image and font loading

7. Performance governance in releases

Add a release gate:

• define acceptable budgets for page weight and script execution
• fail CI when critical thresholds are exceeded
• re-check key landing pages after each deployment

This prevents silent performance decay over time.

Priority order if time is limited

1. Fix oversized media on top landing pages

2. Reduce blocking JS and third-party scripts

3. Improve cache policy and CDN setup

4. Resolve major layout shift issues

Bottom line

Performance work compounds. Small, consistent technical improvements produce stronger SEO durability, better UX, and higher conversion efficiency.