Does page weight matter if your Core Web Vitals scores are good?

Question

At my company, we've done an excellent job showing people the value of using user-based metrics like the Core Web Vitals for performance testing. But this has also become a bit of a two-edged sword.

According to the Google Search Console, mPulse, CrUX etc, we have excellent CWV scores.

My concern is that the page weight of our homepage and other CMS content heavy pages is around 5mb, on the small end. Sometimes if they go crazy with videos and haven't been paying attention, they can balloon up into the 15mb range. But because our CWV scores are good, it's hard to get anyone to care and take action.

From a user's standpoint (and thus, from my standpoint as the supposed performance expert), if all that weight is lazy loaded and the page still appears fast, does it really matter?

Answer 1

It really depends on how you define "matter".

From an SEO perspective, Google Search does not take page weight into consideration, so from that perspective, it doesn't matter. (Note: I do not work on Google Search, so this is based on my understanding of public information.)

From a UX perspective, as measured by the Core Web Vitals metrics, it also does not matter because none of those metrics specifically take page weight into account.

That being said, if a user who visits your site is on a metered data plan, then it would absolutely matter to them if they're having to load things that are not actually needed for the experience, or if the assets are not optimized so they're larger than they have to be.

In short, I think it's important for you as the site owner to define what metrics are important to optimize for. There is not a one-size-fits-all definition of what should "matter" for all websites.