WebPerf Snippets Toolkit
A collection of 47 JavaScript snippets for measuring and debugging web performance in Chrome DevTools. Each snippet runs in the browser console and outputs structured, color-coded results.
Skills by Category
| Skill | Snippets | Use when |
|---|---|---|
| webperf-core-web-vitals | 7 | Intelligent Core Web Vitals analysis with automated workflows and decision trees |
| webperf-loading | 28 | Intelligent loading performance analysis with automated workflows for TTFB investigation (DNS/connection/server breakdown), render-blocking detection, script performance deep dive (first vs third-party attribution), font optimization, and resource hints validation |
| webperf-interaction | 8 | Intelligent interaction performance analysis with automated workflows for INP debugging, scroll jank investigation, and main thread blocking |
| webperf-media | 3 | Intelligent media optimization with automated workflows for images, videos, and SVGs |
| webperf-resources | 1 | Intelligent network quality analysis with adaptive loading strategies |
Quick Reference
| User says | Skill to use |
|---|---|
| "debug LCP", "slow LCP", "largest contentful paint" | webperf-core-web-vitals |
| "check CLS", "layout shifts", "visual stability" | webperf-core-web-vitals |
| "INP", "interaction latency", "responsiveness" | webperf-core-web-vitals |
| "TTFB", "slow server", "time to first byte" | webperf-loading |
| "FCP", "first contentful paint", "render blocking" | webperf-loading |
| "font loading", "script loading", "resource hints", "service worker" | webperf-loading |
| "jank", "scroll performance", "long tasks", "animation frames", "INP debug" | webperf-interaction |
| "image audit", "lazy loading", "image optimization", "video audit" | webperf-media |
| "network quality", "bandwidth", "connection type", "save-data" | webperf-resources |
Workflow
- Identify the relevant skill based on the user's question (use Quick Reference above)
- Load the skill's skill.md to see available snippets and thresholds
- Execute with Chrome DevTools MCP:
mcp__chrome-devtools__navigate_page→ navigate to target URLmcp__chrome-devtools__evaluate_script→ run the snippetmcp__chrome-devtools__get_console_message→ read results
- Interpret results using the thresholds defined in the skill
- Provide actionable recommendations based on findings