Bug 1367205 (QF-Polymer)

Very poor Polymer performance compared to Chrome




2 months ago
8 days ago


(Reporter: sstangl, Unassigned)


(Depends on: 1 bug, Blocks: 1 bug, {meta})

Firefox Tracking Flags

(Not tracked)


(Whiteboard: [qf:?], URL)



2 months ago
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.


2 months ago


2 months ago
Alias: QF-Polymer

Comment 1

2 months ago
Polymer has to polyfil web components on FF.  Chrome implements the web components APIs natively so probably a lot of savings come from that.

Comment 2

2 months ago
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

Comment 3

2 months ago
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.
Depends on: 811542
Do we have a timeframe for webcomponents? Maybe a subset implementation gets us far enough?
Flags: needinfo?(overholt)
(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.
Flags: needinfo?(overholt)
Component: General → DOM
Keywords: meta
Priority: -- → P2


a month ago
See Also: → bug 1366370
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