Check library · Speed and Core Web Vitals
Server response is slow
Why it matters
Time to first byte sits in front of every other performance metric.
What to do about it
Cache at the edge, or fix whatever the server is doing before it answers.
This one is reported rather than applied. It needs a judgement a person has to make, and applying it automatically would be a change to your site that nobody decided on.
How it is weighted
These are the values the scoring actually uses, not a description of them. Priority is derived from all three rather than chosen, which is why a high-impact, low-effort finding surfaces above a severe one that would take a quarter to fix.
- Severity
- high
- Impact
- 55% of the weight this category can carry
- Effort
- 50%, where 100% is a project rather than a change
- Confidence
- 80% that a hit is a real problem rather than a pattern we misread
- Area
- Speed and Core Web Vitals
Other checks in Speed and Core Web Vitals
mediumPage weight is largeheavy_pageneeds a decisionmediumVery large JavaScript payloadexcessive_javascriptneeds a decisionmediumRender-blocking stylesheets and scriptsrender_blocking_resourcesneeds a decisionlowImage uses a legacy formatimage_legacy_formatfix writtenlowImage has no width and heightimage_no_dimensionsfix writtenlowBelow-the-fold images load eagerlyimage_no_lazy_loadingfix written
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