Bytes by resource type
The page weight split by resource type: HTML, JS, CSS, images, fonts, media.
At a glance the headline numbers for Bytes by resource type
The page weight split by resource type: HTML, JS, CSS, images, fonts, media.
Scripts are 31.9% of all requests. Images are 30.7%.
The bytes by resource type mix who uses what, and how fast each group loads
Bytes by resource type. On the fleet: 31.9% script, 30.7% image, 13.4% stylesheet. 97.3% of sites use at least one script.
By count script leads (31.9%); by bytes it is image (63.3%). computed
Passing INP per bucket every category and count level at once - color is the pass rate
Each row is a category, each column its own count bucket (few on the left, many on the right); the cell is the share of those sites passing INP.
No category moves the INP pass rate much, however many a site ships. computed
Few vs many - does quantity cost INP? the pass rate with few vs many of each category
Per category: the pass rate among pages with FEW of it (hollow ring) against pages with MANY (solid dot), worst trend first. Thin buckets are excluded from the endpoints.
More Xhr costs the most: the INP pass rate falls from 99% with few to 95% with many. computed
Why this matters for the Core Web Vitals, and where to start fixing it
The total page weight tells you the size of the problem. The split per resource type tells you which Core Web Vital pays for it. Image bytes mostly cost LCP. They compete for bandwidth with the hero image and make it load slower. Script bytes are the expensive ones. After the download the main thread still has to parse and execute them, so a script-heavy mix shows up in INP. CSS blocks rendering until it is loaded. Font bytes delay text rendering.
That is why the same total weight can produce very different vitals. A content site with mostly image bytes needs modern formats and lazy loading. A web app with mostly script bytes needs deferral and dead code removal. The mix tells you which problem you have.
How does this affect the Core Web Vitals?
Bytes by resource type correlates with the LCP. With Manifest, 89% of sites pass the LCP. With Prefetch, 77% do.
Chrome field data from 94,910 sites, representing millions of real page loads. How we measured.