[Performance] Impact of Eager Modals on LCP and CLS

[yesil]

While analyzing the performance of some commerce pages, I noticed that eager loading of modals is contributing to a higher LCP.

Proposal:
Can we consider delaying the rendering of modals until after the LCP event? This would include deferring the loading of modal.js and any associated processing.

Additional Observation:
The sign-in button in the global navigation is causing a CLS, which is currently being accounted for in the LCP calculation when the page has an eager modal. This further impacts overall page performance negatively.

e.g: https://pagespeed.web.dev/analysis/https-main--cc--adobecom-hlx-live-fr-products-photoshop/ba081jhndj?form_factor=mobile

The Sign-in button doesn't always appear in the report but I was able to confirm it locally:

[yesil]

At https://main--cc--adobecom.hlx.live/fr/products/photoshop?martech=off&georouting=off
From the screenshot above, it seems caas.css is also causing a slight CLS.