High CPU usage on Youtube main page

[ferjm]

I see ~400% of CPU usage after opening https://youtube.com in Servo.

I'm not sure if this is related, but I see these errors in the console:

[2018-12-05T20:59:42Z ERROR script::dom::bindings::error] Error at :0:0 uncaught exception: YQ@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3204:168
VQ@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3201:59
WQ@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3199:76
sS@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3301:319
QT@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3451:314
g.ST.prototype.init@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:6131:39
g.h.St@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:5772:85
SU@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:3541:307
@https://www.youtube.com/yts/jsbin/player_ias-vfl_RGK2l/en_US/base.js:6237:160
rba/a.R@https://www.youtube.com/yts/jsbin/www-en_US-vfl76chmX/base.js:487:235
Ia/<@https://www.youtube.com/yts/jsbin/spf-vflhSOzLf/spf.js:13:477
q@https://www.youtube.com/yts/jsbin/spf-vflhSOzLf/spf.js:8:247
Ia@https://www.youtube.com/yts/jsbin/spf-vflhSOzLf/spf.js:13:441
Ra@https://www.youtube.com/yts/jsbin/spf-vflhSOzLf/spf.js:16:335
l/<@https://www.youtube.com/yts/jsbin/spf-vflhSOzLf/spf.js:7:132

[ferjm]

This makes the main page unusable. You cannot click on any link and scrolling is slow.

[hungrymonkey]

https://twitter.com/cpeterso/status/1021626510296285185

YouTube page load is 5x slower in Firefox and Edge than in Chrome because YouTube's Polymer redesign relies on the deprecated Shadow DOM v0 API only implemented in Chrome. You can restore YouTube's faster pre-Polymer design with this Firefox extension

Christ Peterson