Check library · Speed and Core Web Vitals
Render-blocking stylesheets and scripts
Why it matters
Anything parsed before first paint delays first paint.
What to do about it
Inline the critical CSS, defer the rest, and add async or defer to scripts.
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
- medium
- Impact
- 40% 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
highServer response is slowslow_responseneeds a decisionmediumPage weight is largeheavy_pageneeds a decisionmediumVery large JavaScript payloadexcessive_javascriptneeds 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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