RegExp: String replace operations using Regular Expressions are slow in EDGE and IE9+ for large strings

[manishbarman]

RegEx evaluator in Chakra Core seems to perform slowly (takes more than double the time) for large strings compared to Chrome.

Standalone test case to reproduce the issue
http://jsfiddle.net/Lwa0t5rp/3/

Sample test output extract
Chrome: v53.0.2785
regex 1: 2.8100000000000214 regex 2: 1.3566666666666833 ( rows : 4096 string length:2569724)
regex 1: 3.7816666666666756 regex 2: 2.7783333333333453 ( rows : 8192 string length:5146108)
regex 1: 7.228333333333315 regex 2: 6.0666666666666815 ( rows : 16384 string length:10337180)
regex 1: 14.333333333333334 regex 2: 11.303333333333436 ( rows : 32768 string length:20741020)
regex 1: 27.843333333333362 regex 2: 29.471666666666692 ( rows : 65536 string length:41548700)

EDGE: v38.14393.0.0 EdgeHTML 14.14393
regex 1: 5.059881559322018 regex 2: 2.975162459528974 ( rows : 4096 string length:2205180)
regex 1: 9.785139583279791 regex 2: 6.15836259479958 ( rows : 8192 string length:4417020)
regex 1: 19.578437506784894 regex 2: 11.69511229889531 ( rows : 16384 string length:8879004)
regex 1: 44.75823350880349 regex 2: 25.138609542494805 ( rows : 32768 string length:17824668)
regex 1: 78.02833970539177 regex 2: 47.913274211683984 ( rows : 65536 string length:35715996)

IE11 performance is far worse
IE11: v11.187.14393.0
regex 1: 17886.814111784788 regex 2: 5.659022724537256 ( rows : 4096 string length:2205180)

[dilijev]

Thanks for bringing this to our attention! @rajatd has been doing some work on RegEx lately and it's possible that some of the gap has already been addressed in the latest builds of Chakra and Edge. We will keep this test in mind.

Unfortunately we won't be doing any performance work on IE11 going forward.

[MikeHolman]

@LouisLaf FYI

[dilijev]

@ricobbe Is this related to your current investigation?

[ricobbe]

It might well be; I don't yet know if my investigation involves particularly large strings. I'll take a look, though -- thanks!