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Actionable Performance Audit Checklist

This document provides a hands-on checklist for auditing and optimizing the performance of the InsightHub project. Use it regularly to ensure a fast and responsive user experience.

Frontend (SvelteKit/TypeScript)

  • [ ] Lighthouse Score:
    • Action: Run a Lighthouse audit in Chrome DevTools on key pages (homepage, dashboard).
    • Review Question: Are the Performance, Accessibility, Best Practices, and SEO scores all above 90? What specific, low-hanging fruit does the report suggest?
  • [ ] Bundle Size & Composition:
    • Action: Run npm run build and then npx vite-bundle-visualizer to analyze the final bundle composition.
    • Review Question: Are there any unexpectedly large libraries in our bundle? Can we replace heavy libraries (like moment.js) with smaller alternatives (like date-fns)?
  • [ ] Image & Asset Optimization:
    • Review Question: Are all images served in modern formats (like WebP) and appropriately sized for their containers?
    • Action: Use the <enhanced:img> component for static images to automate optimization. For dynamic images, ensure they are compressed before upload.
  • [ ] Component Loading Strategy:
    • Review Question: Are we loading large, non-critical components (e.g., complex charts, modals) immediately?
    • Action (Code Review): Use Svelte's {#await import('./MyComponent.svelte')} syntax to lazy-load components that are not visible on initial page load.
  • [ ] CSS Performance:
    • Review Question: Is our critical CSS inlined for the fastest initial render? (SvelteKit often handles this well).
    • Action (Code Review): Are we using complex, deeply nested CSS selectors? Simplify selectors to improve style computation speed.

Backend (Python/FastAPI)

  • [ ] API Response Time:
    • Action: Use a tool like Postman or curl with timing flags to measure the response time of critical API endpoints.
    • Review Question: Are any endpoints consistently taking longer than 500ms to respond? Can the logic be optimized?
  • [ ] Database Query Performance (Supabase):
    • Action: Use EXPLAIN ANALYZE on slow queries directly in the Supabase SQL Editor to understand their execution plan.
    • Review Question: Are we missing indexes on columns used in WHERE, JOIN, or ORDER BY clauses?
    • Review Question (N+1 Problem): In loops that fetch data, are we making one query per item instead of a single batch query? (e.g., fetching 10 posts and then making 10 separate queries for each post's author). Consolidate these into a single JOIN query.
  • [ ] Caching Strategy:
    • Review Question: Are there API endpoints that return static or infrequently changing data?
    • Action: Implement a caching layer (e.g., Redis) for these endpoints to serve responses from memory, avoiding repeated computation or database hits.
  • [ ] Load Function Optimization (SvelteKit +page.server.ts):
    • Review Question: Is our load function waiting for multiple, independent data fetches sequentially?
    • Action (Code Review): Run independent promises in parallel using Promise.all() to reduce the total wait time.
    • Action (Code Review): For non-essential data, stream promises directly to the client instead of awaiting them in the load function. This allows the page to render faster while the less critical data loads in the background.

Infrastructure & Network

  • [ ] Time to First Byte (TTFB):
    • Action: Use a tool like WebPageTest or GTmetrix to measure TTFB from different locations.
    • Review Question: Is the TTFB consistently under 600ms? If not, investigate server-side processing or database bottlenecks.
  • [ ] Content Delivery Network (CDN):
    • Review Question: Are our static assets (JS, CSS, images) being served via a CDN? (Supabase handles this for storage, but verify for other assets).
  • [ ] HTTP/2 or HTTP/3:
    • Action: Check the "Protocol" column in the Chrome DevTools Network tab to ensure assets are served over h2 or h3.

CI/CD (GitHub Actions)

  • [ ] Workflow & Test Duration:
    • Action: Review the "Actions" tab in GitHub. Are our CI/CD pipelines taking an excessively long time to complete?
    • Review Question: Can we run tests in parallel or optimize slow build steps to get faster feedback?