cers reported this on IRC. For the "split" micro-benchmark below we have: JM+TI : 1198 ms Ion : 2594 ms The problem is that these functions call GetTypeCallerInitObject, which calls currentScript. We want to self-host map and filter eventually, and we could specialize split. function f() { var s = ""; var t = new Date; for (var i=0; i<10000000; i++) { s.split(s); } print(new Date - t); } f();

The real issue is that we end up in GetPcScript. See bug 728045.

Bleh - once again, I think this is indicative of a design flaw in the engine, and not a problem with GetPcScript. Though if there's no easy workaround for these maybe we should hack something up, like a one-entry cache.

Well, by "real issue" I meant "where the time gets spent". No opinion on how to fix it. ;)

With Bug 794679 fixed, local results are 1488 ms with --no-ion, 1579 with ion.

Well, it's still slower, just not as much slower, right?