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Measures server response time (TTFB)
Rule IDperf/ttfb
CategoryPerformance
ScopePer-page
Severitywarning
Weight7/10

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Solution

Time to First Byte (TTFB) measures how quickly your server responds. Slow TTFB indicates server/backend issues. Thresholds (Core Web Vitals):
  • Good: < 600ms
  • Needs improvement: 600-1000ms
  • Poor: > 1000ms
Fixes for slow TTFB:
  • Enable server caching (Redis, Varnish, CDN)
  • Optimize database queries
  • Use CDN for static assets
  • Upgrade server resources
  • Reduce server-side processing
  • Enable HTTP/2 or HTTP/3
  • Use edge computing (Cloudflare Workers, Vercel Edge)

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Options

This rule supports the following configuration options:
OptionTypeDefaultDescription
good_thresholdunknownundefinedGood TTFB in ms
poor_thresholdunknownundefinedPoor TTFB in ms

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Configuration Example

squirrel.toml
[rules."perf/ttfb"]
good_threshold = undefined
poor_threshold = undefined

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Enable / Disable

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Disable this rule

squirrel.toml
[rules]
disable = ["perf/ttfb"]

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Disable all Performance rules

squirrel.toml
[rules]
disable = ["perf/*"]

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Enable only this rule

squirrel.toml
[rules]
enable = ["perf/ttfb"]
disable = ["*"]