Comment #7 on issue 2275 by [email protected]: Disappointingly bad
switch performance on V8
http://code.google.com/p/v8/issues/detail?id=2275
Just to get a few more data points, I've hacked the original benchmark.js
to use an array for dispatching (see attachment). The numbers on the
various browsers:
Firefox 14.0.1: switch = 66 calls/sec, array = 37 calls/sec
Chrome 21.0.1180.57: switch = 4 calls/sec, array = 46 calls/sec
Chrome 22.0.1230.0: switch = 4 calls/sec, array = 55 calls/sec
This means that using arrays instead of a switch statement is currently
your best bet, it works OK on both browsers. I guess that the performance
impact of the dispatch mechanism gets more negligible when the various
cases do more than just returning a constant value.
Note that I'm not stating that v8 shouldn't do better for switches, but
this probably won't happen in the near future, so don't hold your breath.
Attachments:
benchmark-array.js 8.3 KB
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