> This isn't true?

Heh, I’m not sure why you would think this- there is some sharing of resources for browser tabs but not a lot when you consider the javascript runtimes memory requirement and sandbox isolation features.

Safari is perhaps the best (or worst- depending on how you look at it) for sharing resources between tabs and weakening the sandbox for that, but I regularly see tabs running at over 1.5GiB of RAM (Tab+Renderer in Activity Manager).

It just becomes harder to track if its part of the normal browser, I think. Many browsers don’t show you a true per tab breakdown (firefox doesn’t) and often there are multiple threads per tab making the aggregation difficult (Chrome/Safari to some extent).

Even the “tab resource monitor” extensions and menus that exist only show part of the resources a tab is using, basically its DOM and in memory resources but not its renderer, runtime or other harness’