If native performance is "very very very" not fast enough then that's supercomputer work and it doesn't really matter if WASM is 3x native or 0.3x native. So that context should be where you're the least depressed.
And today's supercomputer work was impossible in the late 90's.
That doesn't really change my argument. When you're looking at languages that are used for small tasks today, their speed doesn't have much relevance to how vastly bigger tasks are accomplished. And by the time those tasks can be run on a laptop, WASM implementations are going to be much better and we still might not be using it at all for those larger tasks.
today's laptop work is late 90's supercomputer's work (and it was even more depressing back then).