On Wed, Feb 26, 2020 at 9:29 PM Maciej Stachowiak <m...@apple.com> wrote:
> I also suggest to start with "first-paint" as it's perhaps a bit less > "internal" than FCP, and can provide a performance-regression metric with a > lesser degree of risk regarding exposing internals / privacy. > > > First paint that’s not first meaningful/contentful paint is not a very > good performance metric IMO. Who cares that a paint happened if it doesn’t > have any image or text content? > I think it's meaningful as a general regression metric, albeit less useful than FCP. Web developers are scrambling for any RUM information they can use... > I also don’t think this exposes less. The privacy risk here is exposing > timing data that might be usable for fingerprinting. > Yes, I think that privacy-relevant timing information is already available through resource timing (window.performance.getEntries("resource")). But we'll see what the privacy experts come up with. > What was deprecated was "first meaningful paint" (FMP). FCP was not > deprecated and has been in wide use for some time. > > What’s the difference between First Meaningful and First Contentful? > FMP had the notion of "primary" content; e.g. it was ignoring navbars/headers, and trying to figure out when the main content of the site has been rendered. As noted, FMP is deprecated. FCP is a lot more transparent in what it measures. We will discuss with Apple’s privacy experts what they think of the privacy > risk. I’m just giving you a rain check for results of this discussion. > Got it, Looking forward :)
_______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev