Perf Web Optimization

What it does

This skill assists with web performance optimization, providing a systematic approach to improving website speed and user experience. It guides users through a process of measurement, identification of bottlenecks, prioritization of fixes, implementation of optimizations, and verification of results. The skill focuses on key metrics like Largest Contentful Paint (LCP), Interaction to Next Paint (INP), Cumulative Layout Shift (CLS), and Time To First Byte (TTFB) to ensure optimal performance.

When to use it

• When website load times are slow or impacting user engagement.
• To proactively improve web page speed before launch or during development.
• For identifying and addressing specific performance bottlenecks like large images, fonts, or third-party scripts.
• During code reviews to ensure optimization best practices are followed.
• When needing guidance on optimizing image loading strategies (eager vs. lazy).

Key capabilities

• Provides a structured "Measure → Identify → Prioritize → Implement → Verify" workflow for web performance optimization.
• Offers target metrics and thresholds for LCP, INP, CLS, and TTFB.
• Suggests quick wins including image optimization (WebP/AVIF formats, responsive images), font loading techniques (preconnect, non-blocking fonts), and third-party script management (deferring execution).
• Includes guidance on critical CSS inlining and deferred loading.
• Provides instructions for bundle analysis using tools like webpack-bundle-analyzer and vite-bundle-visualizer.
• Suggests alternatives to heavy JavaScript libraries like Moment.js and Lodash.
• Demonstrates code splitting patterns for React, Next.js, and Vite/Rollup.
• Offers advice on setting appropriate caching headers for static assets, HTML, and API responses.

Example prompts

• "How can I improve the LCP of my website?"
• "What are some quick wins for optimizing image loading?"
• "Suggest alternatives to Moment.js for date manipulation."
• "Show me how to defer third-party scripts on my page."

Tips & gotchas

• This skill provides guidance and code snippets; it does not automatically implement optimizations.
• The suggested quick wins may require adjustments based on the specific website's architecture and content.
• For detailed performance audits, reports, and budget setting, use in conjunction with the perf-lighthouse skill.