Safari is fast and performant but once you load a heavy web app that uses a lot of memory safari will kill the tab. It’s incredibly frustrating to have a page reload with a banner simply saying the site was using too much memory and was reloaded. Especially when you’re on a maxed out MacBook with plenty of resources.
I will also note that Safari is almost /too/ deeply integrated in the system, when I'm running a high-stress task elsewhere, my browser would jitter or hang, the same couldn't be said for chromium, for some reason.
I agree, in practice I see this occasionally on gigantic GitHub pull requests with 1000+ files, or very clunky Atlassian/Confluence pages. I'd say both sides need to work on their resource management!
(On that note, many complaints about Safari I hear from developers fall on my ears as "I don't care about web compatibility!" as it has never NOT been the case on the web that you need to care about feature support and resource management.)