I saw this recently primarily with Firefox and (presumably?) Firefox may have been updated to fix the issue because it is thankfully not happening anymore.

When it did happen though, it seemed ludicrous: that a single app could in a matter of literally minutes start burning through gigabytes of memory, to the point where the entire system seems to freeze with no option except to kill Firefox (and everything it may be doing) to continue. And, like the author, I had started keeping Activity Monitor open so I could pre-kill Firefox at a point when I knew it would probably start to be pushing it.

It never feels good to baby-sit a machine. It feels even worse when it’s an expensive new machine. And it means that the operating system is failing at its most basic task (arguably the entire point of having an operating system) — to manage resources well.