Earlier quoted context omitted.
I'm not sure where the hangup is, but I've found that Edge is fast as hell for initial page startup, but lags behind quite a lot when under heavy load. I've seen the benchmarks but in my experience it just... lags... For example, on the kangax ES6 compatibility table [1]. On chrome clicking a column takes less than a second, on Edge (i'm on an up-to-date Windows 10 machine, no preview stuff) it loads faster than in c…
I know between Chrome and Firefox for a particular project of mine (which is a bit old now), Firefox ran raw JS faster, but Chrome could update its DOM faster. FF would spend much more time when many updates needed to happen in a large column of divs (10k+). Raw JS speed isn't everything.
But for a more "pure" js example, I have an app which does some image processing in the browser using the canvas ImageData stuff and typed arrays.
For whatever reason my test case completes in about 3 seconds in chrome, 3 to 4 seconds in FF, 11 seconds in IE11, and 6 seconds in Edge.
I've profiled the hell out of it and i just can't figure out the reasoning for it, but it's there. (and as a side note, having the dev tools open in Edge obliterates javascript performance, my test case was taking 30+ seconds to run when i had the dev tools open and it took me longer than i'd like to admit to figure that one out)
I have a feeling the problem is that i'm optimizing for V8 because i know it the best, and i'd much rather not do that if possible.