This is not "random metric", and I find that talking too much about "metrics that matters to end user" in abstract is muddying the waters. Here are the important performance metrics for end users:
- It's slower than my speed of thinking / inputting. If I can press keys faster than they appear on the screen, it's completely broken.
- I can no longer have all the applications I need opened simultaneously, because together, they exhaust all the system resources. Even though I have a faster computer now, and 5 years ago, equivalent set of applications worked together just fine.
- My laptop/phone battery seems to be down to 50% in an hour.
- Your webpage takes 5+ seconds to load, even though it has just a bunch of text on it.
- Your webpage is slowing down / hanging my browser.
- I'm on a train / in a shopping mall, and have spotty connection. I can't load your webpage even though if I serialized the DOM, it would be 2kb of HTML + some small images, because of all the JS nonsense it's loading and doing.
Most users cannot distinguish when websites are hogging resources. Metrics like the first paint, first meaningful paint and time to interactive are usually more important than memory usage.
Memory usage sure will help but it is mudding water more than more specific user-centric metrics. Sometimes for business applications(Slack) feature richness and in-app performance is more important than memory usage. It all depends on website/application and throwing tantrum about memory usage do not help.
> Most users cannot distinguish when websites are hogging resources.
Of course they can. The user happily works on their computer. They open your site. Their browser (or entire computer) starts to lag shortly after. Doesn't take a genius to connect the dots, especially after this happening several times.
> Metrics like the first paint, first meaningful paint and time to interactive
Those are metrics for maximizing amount of people not closing your site immediately; not for minimizing the misery they have to suffer through.
> Of course they can. The user happily works on their computer. They open your site. Their browser (or entire computer) starts to lag shortly after. Doesn't take a genius to connect the dots, especially after this happening several times.
Most users have 20 and more websites/tabs open at the same time. Most users do not even know what is a memory. Funny enough for most users, after initial load JavaScript rich SPA will be perceived as more snappy than a server-side rendered page but it will use more resources on the client side.
> Those are metrics for maximizing amount of people not closing your site immediately; not for minimizing the misery they have to suffer through.
These metrics are what is important for users. Users do not care how much resources your application consumes. What matter is performance perceived by the users.
Speed matters to end users. 12 Mb will not load in under a second for most users. Unless you absolutely dominate the field or have some specific redeeming feature, your users will move to your competitor services.
