If you are wondering why YouTube is loading so slowly on Microsoft Edge, Safari, or Firefox compared to Googles Chrome Browser. Here is the answer for you As Google redesigned the YouTube experience last year, but the site still uses an older shadow API that is only used in Chrome, which makes other browsers render YouTube much slower. Chris Peterson, the technical program manager at Mozilla (who oversees the Firefox browser), finally gave a detailed analysis and confirmation of what we all have experienced: YouTube is slower on Firefox and Edge.

Google’s recent redesign of YouTube, which is named Polymer, uses the “Shadow Document Object Model (DOM)” version-zero API, which is a form of JavaScript. It’s that dependency on what is an older version of Shadow DOM that is the issue. Even Polymer 2.x supports Shadow DOM v0 and v1, but YouTube, ironically, has not yet been updated to the newer refreshed Polymer.

Chris Peterson explained:

“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,”

Chris Also explained “YouTube serves a Shadow DOM polyfill to Firefox and Edge that is, unsurprisingly, slower than Chrome’s native implementation. On my laptop, the initial page load takes 5 seconds with the polyfill vs 1 without. Subsequent page navigation perf is comparable,”

Google could update YouTube to use Polymer 2.0 or even 3.0 which both support the deprecated API, but the company has decided to stick to using Polymer 1.0 that was originally released in 2015. It’s an odd decision, especially when you consider that Polymer is an open-source JavaScript library that is developed by Google Chrome engineers.

According to Peterson, this decision by Google results in Edge and Firefox being up to five times slower than Chrome – specifically with comments and related material seemingly taking forever to load. And the solution we would need to return to the old YouTube interface and disable this alleged throttling bug on Edge and Firefox browser. To do this

Note: Reverting back will mean you’ll lose the updated design and the dark mode feature in YouTube.

Open youtube.com on Edge browser, And press F12 key to launch the Developer mode option. Navigate to Debugger tab and  Double tap Cookies to expand the sub-menu.

YouTube run slow on Microsoft Edge
YouTube run slow on Microsoft Edge

Here under Cookies double click on opened page URL. In the middle area where values are displayed, find PREF and modify its value as al=en&f5=30030&f6=8. That’s all close Edge Developer mode and refresh the page. Let us know this time edge load the youtube page faster than before?

If you are Firefox users download YouTube classic extension to force the site (Youtube) to load properly,

Also, you can try solution below If Youtube videos does not play well on Microsoft edge browser, but the audio does just fine. Also Sometimes playing youtube video crashes the Edge browser getting slower, getting lag, etc.

Press Windows + R, type inetcpl.cpl and ok to open Internet properties window.

Here move to Advanced tab And look for the option “Use Software rendering instead GPU rendering”

Check that box, as shown image below and click ok to make save changes.

Use Software rendering instead GPU rendering
Use Software rendering instead GPU rendering

Close and restart Edge browser and now open youtube.com and play any video let us know still browser crashes?

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