Reported by a user on https://www.reddit.com/r/firefox/comments/6cwn5s/gamingyoutubecom_performance_in_firefox_vs_chrome/, it appears that http://gaming.youtube.com takes about twice as long to load in Firefox Nightly as it does to load in Chrome Stable. Taking a profile, https://perfht.ml/2q8dMXv, a significant chunk of time (~1s of 2s) is spent in gaming_polymer.js, which is their deployment of the Polymer framework. An even more dramatic difference can be seen if you visit the Polymer homepage at https://www.polymer-project.org/. Chrome loads that effectively instantly, but Firefox takes between 7-10 seconds. Polymer is a Google library, and it seems that they did not build it with Firefox performance in mind, but we nevertheless must improve the situation.
Polymer has to polyfil web components on FF. Chrome implements the web components APIs natively so probably a lot of savings come from that.
There is a benchmark made by the Polymer team for an older version (0.8; current 1.9) available at http://polymerlabs.github.io/benchmarks/synth/medium-list/runner.html. Running that in Firefox Nightly versus Chrome Stable gives the following timings: > polymer/app.html: > Chrome: 8.9ms; Firefox: 1551.9ms > polymer-0.8-03242015/app-shadow.html > Chrome: 225.7ms; Firefox: 1093.7ms > polymer-0.8-03242015/app.html > Chrome: 253.0ms; Firefox: 307.3ms > polymer-0.8-03242015-class/app.html > Chrome: 208.1ms; Firefox: 304.9ms
The original reporter of the Youtube Gaming performance issue left a comment that may be worth sharing. > Hopefully it will be fixed before polymer is on youtube.com as well, which is currently available as an option on youtube.com/new and performance is pretty much the same as with gaming.youtube.com. So, if Polymer is coming to Youtube, we *really* want to get on top of it. Presumably it will be spreading to other websites as well.
Do we have a timeframe for webcomponents? Maybe a subset implementation gets us far enough?
(In reply to Naveed Ihsanullah [:naveed] from comment #4) > Do we have a timeframe for webcomponents? Maybe a subset implementation gets > us far enough? Looking like end of 2017 for Custom Elements and currently unknown for Shadow DOM.