Firefox Community Forum

As title says, whenever I'm scrolling through any website there's a lot of flickering, did some research and past "fixes" said to turn off smooth scrolling and hardware acceleration, which I tried but all it did was minimise the effects, this flickering has only been happening for the last day or so.

Firefox Developer Edition version - 139.0b1 (64-bit) Nightly version - 140.0a1 (2025-04-30) (64-bit)

Youtube video showing what's happening

I use several browsers and when it comes to functionality I consider FFox to be the best however with 1 major drawback - it's speed / lag issues which is why I stopped using it as my primary browser and only as secondary one

I can have 2 different Chromium based browsers open simultaneously and while this impacts the performance somewhat if I open Firefox and another browser responsiveness grinds to a halt (sometimes even crashes)

Even just starting Firefox by itself takes 5x as long as other browsers

So I'm wondering is Firefox just more resource intensive or is there something wrong with my setup?

The main difference between my Firefox install and my other browsers is the number of Bookmarks (10000s) due to me having it installed for much longer so is it possible for a large number of Bookmarks to slow the browser down even when not open ?

Other possible causes I read elsewhere are 'Cookies and site data' (currently around 50mb)

I clear the 'Temporary cached files' & 'Browsing history' on regular basis so they shouldn't be an issue

The add-ons I have installed are NoScript , Ublock Origin & Firefox Color

In regards to troubleshooting is it possible to install a 2nd install on the same system simultaneously without overwriting the current one ?

Thanks

Hello everyone. Google keeps telling me there is unusual traffic coming from my computer and requires captcha all the time. It only happens with Firefox and only when I launch a search from a blank tab, not from bookmarks. Environment : Firefox (last version) Windows 11 Family (updated), antivirus Bitdefender (support team does not detect any problem).

Please can anyone help me fix that ?

Thks a lot. Edms

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Hello, I can’t scroll anymore when enabling the performance settings ([https://support.mozilla.org/en-US/kb/.../performance-settings] ).

Is this a known bug? Is there any fix?

Thanks!

I made the mistake of clicking a YouTube link via Twitter and now Youtube is convinced my Firefox on my desktop PC is a mobile device. Every tip I see tells me to "just request the desktop version of the site!"; only, that's ONLY a feature in the mobile Firefox app... which I'm NOT using. Every time I go to Youtube's home page: it starts me scrolled down as though it's trying to display on a portrait-mode screen, and only shows 3 videos per row. It's clearly trying to display on a mobile device. If I hold down F5, and force it to refresh for a dozen or so times, for a split second it will display properly before re-setting to mobile mode.

Things I've already done so don't suggest them: - Force refresh teh page - Alreadyd one, didn't work - Clear Website cookies & site data - Already done, didn't work - Restart Firefox - Already done, didn't work - Clear browser cache - Already done, didn't work - Open new private window - Already done, didn't work - Restart Firefox in safe mode - Already done, didn't work - Restore default Firefox theme - Already done, didn't work

The problem apepars to be that Youtube has just reclassified my browser/device as mobile and there's nothing I can do to change it.