NextJS 12.2 decreases LCP for large eCommerce site

[jantimon]

Provide environment information

Live Website ~9 million page visits this month

Describe the Bug

We have just started to investigate but on first glimpse our measurements suggest that it's very likely that NextJS 12.2 is slowing down our LCP significantly from good to needs improvement

If you have any interest in investigating this case together with us (be it free or paid) just let us know :)

Expected Behavior

Same LCP for 12.2 and 12.1

Link to reproduction

https://www.galaxus.ch/en/

To Reproduce

I don't know how you might reproduce the issue - but if you like we could investigate our live system together

[willemliufdmg]

Could be related to:

• SSG pages re-render if middleware is being used #38267

[jantimon]

thanks @willemliufdmg however we are using neither middleware.ts nor etags - so it seems to be a different issue

[11koukou]

Hello,
I am constantly checking my site's web vitals after every release and I can't confirm any LCP decrease, especially significant. Make sure that you are preloading your LCP in case it is an image and that you are using lighthouse/pagespeed for getting useful suggestions about your code