run sup script decoration in a separate task

[ekremney]

Please always provide the GitHub issue(s) your PR is for, as well as test URLs where your change can be observed (before and after):

Fix #

Test URLs:

• Before: https://main--mammotome--hlxsites.hlx.page/us/en/
• After: https://tbt-mitigation--mammotome--hlxsites.hlx.live/us/en/

This PR simply runs sup script decoration in a different event loop task to prevent decorateMain function block the main thread for more than 50ms. This way any other task (ie user interactions) scheduled while decorateMain function being executed won't wait more than 50ms.

Before and after visualized:

[aem-code-sync[bot]]

Hello, I'm the AEM Code Sync Bot and I will run some test suites that validate the page speed. In case there are problems, just click the checkbox below to rerun the respective action.

• [ ] Re-run PSI Checks

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
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[aem-code-sync[bot]]

Page	Scores	Audits	Google
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[aem-code-sync[bot]]

Page	Scores	Audits	Google
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[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[ekremney]

CLS and TBT coming from aem-code-sync is not stable. TBT here is caused by third parties, can be seen better in pagespeed.web.dev

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/

[aem-code-sync[bot]]

Page	Scores	Audits	Google
/us/en/