I don't think it's meant as something that's useful per se because highlighting 5m lines of code at once is unusual, and doing it in a non-deterministic way probably isn't especially helpful, but to show what a browser is capable of it's awesome.
The use case isn't highlighting a huge amount of code, but local re-entrant highlighting.
You generally never need to highlight a whole file, only the part you're looking at. Which by definition must be fuzzy since you don't have the full source, the part you see will not parse as a complete program so you need to guess. This is actually one of the nastier parts of writing a highlighter, and it must be done for every language.
The lesson is that if you're going to be fuzzy you might as well be learned too and the results are pretty good.
This is more useful than it appears at first glance. It would be just as useful running on the CPU, which I'm sure it can.
Great news for a language whose last stable release was 20 years ago
You generally never need to highlight a whole file, only the part you're looking at. Which by definition must be fuzzy since you don't have the full source, the part you see will not parse as a complete program so you need to guess. This is actually one of the nastier parts of writing a highlighter, and it must be done for every language.
The lesson is that if you're going to be fuzzy you might as well be learned too and the results are pretty good.
This is more useful than it appears at first glance. It would be just as useful running on the CPU, which I'm sure it can.