performance Errors
20 error patterns
LCP Too Slow
Largest Contentful Paint.*exceeded.*(?:2500|4000)ms
- •Preload critical images and fonts
- •Optimize server response time (TTFB)
CLS Too High
Cumulative Layout Shift.*(?:0\.1|0\.25).*exceeded
- •Add width/height attributes to images and videos
- •Reserve space for dynamic content with aspect-ratio
TTI Too Slow
Time to Interactive.*exceeded.*(?:3800|7300)ms
- •Code-split and lazy load non-critical JavaScript
- •Reduce main thread blocking time
Bundle Size Limit Exceeded
Bundle size.*exceeded.*limit|maxSize.*budget exceeded
- •Analyze bundle with webpack-bundle-analyzer
- •Code-split routes and heavy dependencies
Lighthouse Score Drop
Lighthouse.*score.*dropped|performance score.*below (\d+)
- •Run Lighthouse in CI to catch regressions
- •Address highest-impact opportunities first
Memory Leak Detected
memory leak detected|Detached.*DOM.*nodes.*growing
- •Check for unremoved event listeners
- •Verify subscriptions are cleaned up on destroy
FID Too High
First Input Delay.*exceeded.*100ms
- •Break long tasks into smaller async chunks
- •Use web workers for heavy computation
TBT Too High
Total Blocking Time.*exceeded.*(?:200|600)ms
- •Split long JavaScript tasks with requestIdleCallback
- •Remove unused JavaScript with tree shaking
Speed Index Too Slow
Speed Index.*exceeded.*(?:3400|5800)ms
- •Optimize critical rendering path
- •Inline critical CSS above the fold
Excessive JS Execution Time
JavaScript execution time.*exceeded
- •Profile with Chrome DevTools Performance tab
- •Implement code splitting at route level
Unoptimized Images
Image.*not properly sized|Serve images in next-gen formats
- •Use responsive images with srcset
- •Convert to WebP/AVIF format
Render-Blocking Resources
Render-blocking resource.*delayed FCP
- •Add async/defer to non-critical scripts
- •Inline critical CSS and lazy-load the rest
Excessive DOM Size
DOM size.*exceeded.*1500 nodes
- •Implement virtual scrolling for long lists
- •Use content-visibility: auto for off-screen content
Layout Thrashing Detected
Layout thrashing detected|forced reflow
- •Batch DOM reads before DOM writes
- •Use requestAnimationFrame for visual updates
Low Cache Hit Ratio
Cache hit ratio.*below|cache miss rate.*high
- •Set appropriate Cache-Control headers
- •Implement stale-while-revalidate strategy
Time to First Byte Too Slow
TTFB.*exceeded.*(?:800|1800)ms
- •Enable server-side caching (Redis/CDN)
- •Optimize database queries on critical path
Third-Party Script Blocking
Third-party scripts.*blocking main thread
- •Load third-party scripts async or defer
- •Use facade pattern for heavy embeds
INP Too Slow
Interaction to Next Paint.*exceeded.*200ms
- •Optimize event handlers to be under 50ms
- •Use startTransition for non-urgent updates
Network Waterfall Pattern
Network waterfall.*sequential requests detected
- •Use rel=preconnect for third-party origins
- •Parallelize independent API requests
Animation Jank Detected
Animation frame.*dropped|jank.*detected
- •Use CSS transforms instead of layout properties
- •Promote elements to own layer with will-change