Eight checks every UGC widget should pass.

1. 1

   Bundle size

   Under 50 KB JS over the wire (compressed).

   Every additional 50 KB on a PDP costs ~80 ms of TTI on a mid-tier Android.

2. 2

   CLS contribution

   CLS < 0.001 attributable to the widget.

   Reserve image dimensions, no late-loaded layout shifts. Bazaarvoice typically adds 0.05+.

3. 3

   INP

   Under 200 ms for any tap on a tile.

   Most widgets break this on cold start. Lazy-mount sub-trees so first interaction is instant.

4. 4

   TTFB on widget API

   P95 under 200 ms from the user’s region.

   Static-cache or stream from the edge — don’t round-trip a database for content that changes every 6 hours.

5. 5

   No layout damage

   Lighthouse PDP score with widget on ≥ PDP score with widget off − 2 points.

   If your widget knocks 10 points off Lighthouse, it’s actively losing you SEO.

6. 6

   Image format

   AVIF or WebP fallback, not JPEG.

   40–70% smaller for the same visual quality. Sanity / Cloudinary / Imgix do this for free; configure them.

7. 7

   Lazy video

   No video loaded until in viewport. No autoplay above the fold on mobile.

   Each MP4 above the fold can cost 1–3 seconds of LCP on 4G.

8. 8

   Third-party scripts

   Load analytics + tag scripts deferred. Audit weekly.

   Most performance regressions come from a tag manager rule someone added at 4pm on a Friday.

Want us to score your live widget for free? Send us your store URL — we’ll run the test and email you a 1-page report.