Open Bug 1088189 Opened 10 years ago Updated 1 year ago

Improve performance of array natives for very sparse arrays


(Core :: JavaScript Engine, defect)





(Reporter: jandem, Unassigned)


(Depends on 3 open bugs)


See bug 1087963 and bug 1045391 for two bugs filed on this very recently.

Fixing this can dramatically improve performance (bug 1087963 has some numbers). V8 has special sparse-array paths for a lot of those natives and apparently IE is also fast (slice at least).

It will add some complexity, but with the right abstractions we can probably do this without duplicating too much code.

The least we should do is instrument the browser and see how often this hits in practice.
No longer blocks: 1045391, 1087963
Depends on: 1045391, 1087963
Another approach is speeding up the current GetElement code path. It won't be as fast but there are probably some easy wins there.
Depends on: 1158767
Depends on: 1384900
Severity: normal → S3
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