884475 - underscore.js performance regression on lodash.js microbenchmark

Status: RESOLVED DUPLICATE of bug 903970

(Core :: JavaScript Engine, defect)

Description

[Chris Peterson [:cpeterson]]

The lodash.js microbenchmark compares the iteration performance of lodash.js and underscore.js:

http://lodash.com/benchmarks

The microbenchmark shows decreasing underscore.js performance in Firefox 22, 23, and 24. The good news is that lodash.js performance increased in Firefox 24.

Some example numbers from my MacBook Pro:

`_(...)` with a number:

* Firefox 21: lodash.min x 7,988,039 ops/sec ±0.93% (89 runs sampled)
* Firefox 22: lodash.min x 7,692,325 ops/sec ±0.94% (83 runs sampled)
* Firefox 23: lodash.min x 7,632,515 ops/sec ±1.57% (86 runs sampled)
* Firefox 24: lodash.min x 9,724,983 ops/sec ±2.83% (82 runs sampled) <- FASTER
* Chrome 27:  lodash.min x 112,424,170 ops/sec ±1.71% (87 runs sampled)

* Firefox 21: underscore-min x 4,026,277 ops/sec ±0.82% (91 runs sampled)
* Firefox 22: underscore-min x 3,994,693 ops/sec ±0.69% (85 runs sampled) <- SLOWER
* Firefox 23: underscore-min x 2,607,601 ops/sec ±0.42% (88 runs sampled) <- EVEN SLOWER
* Firefox 24: underscore-min x 2,580,936 ops/sec ±0.51% (89 runs sampled) <- EVEN SLOWER
* Chrome 27:  underscore-min x 20,094,006 ops/sec ±1.85% (86 runs sampled)


`_(...)` with an array:

* Firefox 21: lodash.min x 6,223,980 ops/sec ±0.26% (92 runs sampled)
* Firefox 22: lodash.min x 6,199,545 ops/sec ±0.54% (89 runs sampled)
* Firefox 23: lodash.min x 5,958,920 ops/sec ±0.50% (85 runs sampled) <- SLOWER
* Firefox 24: lodash.min x 7,344,927 ops/sec ±0.79% (84 runs sampled) <- FASTER
* Chrome 27: lodash.min x 60,022,106 ops/sec ±2.90% (75 runs sampled)

* Firefox 21: underscore-min x 5,338,493 ops/sec ±0.28% (90 runs sampled)
* Firefox 22: underscore-min x 5,098,661 ops/sec ±0.77% (86 runs sampled)
* Firefox 23: underscore-min x 2,304,652 ops/sec ±3.37% (80 runs sampled) <- SLOWER
* Firefox 24: underscore-min x 2,309,458 ops/sec ±3.12% (85 runs sampled) <- EVEN SLOWER
* Chrome 27: underscore-min x 15,957,788 ops/sec ±1.97% (84 runs sampled)

Comment 1

[Boris Zbarsky [:bzbarsky]]

Jan, you said to cc you?  ;)

Comment 2

[Chris Peterson [:cpeterson]]

Bug 903970 is a superset of this bug.