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Within the webperf folks at Google, we've certainly debated if CLS is a performance metric. The loose consensus is that it's not... it's a predictability and UX
by paulirish 5y ago
Within the webperf folks at Google, we've certainly debated if CLS is a performance metric. The loose consensus is that it's not... it's a predictability and UX metric.
Also "Core Web Vitals" is deliberately not scoped to just performance.
That said, it's kinda _easier_ to just simplify and say CLS is a webperf thing and CWV are webperf metrics, because going into the nuance just dilutes the entire framing.
- jameslk 5y ago> Also "Core Web Vitals" is deliberately not scoped to just performance. What do you define as performance then? And how is it different from speed?
- paulirish 5y agoperf is all about making loading fast, scrolling & animations smooth, and interactions responsive. The classic RAIL model captures the scope of perf well. perf and speed are synonyms. CLS is a bit of a loner as there really aren't other metrics these days that also capture non-perf signals. But again, this distinction of CLS as a non-perf metric is for webperf nerds only, IMO.