Low performance because of blurry background

My laptop is having hard times dealing with this new blurry background on any title page (see screenshot below). Page loads slower than before, scrolling is not smooth, and any action is being delayed. Though it happens only on title pages, and only with blurred part visible on my screen, it completely ruins experience of using whole website.

I use latest Firefox on Win 11, but with Edge it is also bad. I've never experienced such bad lags on any other website, besides Youtube in 'ambient mode', which creates similar blurry background effect, but at least on YT it can be switched off easily. So I blame this (CSS?) effect. Is there any way to disable it?