Whether by design or accident, YouTube’s adoption of slower polyfills as part of its Polymer redesign earlier this year has allegedly resulted in 5X slower page-loads on Firefox and Edge than in Chrome.

According to Mozilla’s Technical Program Manager, Chris Peterson, Google is using the Shadow DOM V0 API that’s implemented natively only in Chrome, and not in either of the other aforementioned browsers.

The slowness, however, only seems to affect the initial page load, while subsequent navigation performance is ‘comparable’, says Peterson.

Peterson also lays out a relatively simple workaround to fix the problem – an add-on called YouTube Classic that restore’s the streaming site’s faster pre-Polymer design. The add-on, which is now available on the Mozilla repository, was first launched back in May, and is currently on version 1.2.

Peterson also helped out Edge users by recommending an user script called ‘YouTube Restore Classic’. As is the case will all such scripts, users will need to install the TamperMonkey extension to get it to work. It’s worth noting that similar scripts are also available for Firefox, and users can install extensions like GreaseMonkey or ViolentMonkey to run those scripts automatically.

While the adoption of its Polymer library is expected to help YouTube introduce new features faster, the fact that it is slowing down the service on non-Chrome browsers is bad news for the company that has just been handed not only a multi-billion dollar fine by the EU for anti-competitive trade practices, but also a Rs. 136 crore fine by the CCI (Competition Commission of India) earlier this year for ‘search bias’.