There’s hardware video encoding/decoding support. I used a Pi3b+ to transcode video for a while and would easily get 2x or better on full 1080p video. The 4 is better and I’ve heard even better on the 5, but I’ve not had a compelling reason to spend that much to find out.
Yet I've still been unable to achieve that despite trying multiple distros. Only Android of all things has successfully played YouTube (via smart tube) and video without any issues. I've also yet to see video evidence of smooth playback aside from one person on YouTube (Computers Explained I think), and it was only on Raspberry Pi OS. Which in fairness I kinda do too, but it takes like 12 seconds average to load a webpage on their version of Firefox (no added extensions) and either 5 or 30 on Chromium for some reason.
I've been trying to set the Pi as a htpc (that's not a lobotomized Kodi box) that can also do minor streaming and a few other things, for 5 days and counting. I made a nice click friendly desktop with Manjaro KDE for Pi, and the OS itself is snappy and fast. But any major video graphical elements and it becomes a geriatric Commodore 64.
I know (read:guess) it must be that something going wrong with hardware acceleration, but just can't figure it out. Maybe my Pi is cursed.
Even on the Pi 5 the basic desktop environment in RPI OS with hardware acceleration working feels sluggish. I'm not sure if it's some weird power savings thing, but the pi just drops frames whenever it feels like it.
But I'm just talking about puttering around in the basic desktop environment, not even with a web browse. Just dragging around the file browser it will randomly lag for absolutely no reason.
My Pi5 plays 1440p60 YT in Firefox with zero issue, from a high-performance SD card. The OS is sluggish, as another poster had mentioned. It could use an SSD.
My bad. Only slept 3 hours trying to get things to work last night. And 6 before that.
I had already resigned to just getting an Intel n100 mini PC for my purposes, but I might take another crack at it with your recommendations in the future, after I get some rest and stop dreaming of pies in the sky.
Except Raspberry OS. It's still a bit sluggish for me. Manjaro KDE has been the fastest so far.
Falkon just uses Chromiums web engine and strips everything else, they don't use Manifest V3 as they have their own extension system (although that isn't really mature). It comes with a built in adblocker that works fine for browsing, but youtube ads can't be blocked. I recommend Falkon for web browsing, but I wouldn't use it if all you want to do is watch youtube I would use a browser that supports h264ify. For browsers that do use chromiums web extension api there is a version of h264ify, which you will need for hardware acceleration.
My experience is similar. I don't play YouTube videos on my 4B with 8GB of RAM very often. When I do, I make sure it's well less than a quarter of my 1920x1080 screen. (I use a tiling window manager, so I usually just make my browser window the top-left quadrant of my screen and don't theater-mode or anything.) And I often reduce the quality to 480p or whatever.
If I'm going to watch something longer than a few minutes and want to be doing other things on my Raspberry Pi while the video is running, I'll just pull it up on my phone propped next to my monitor.
Damn! My 3 and 4b are running headless, but my 5 has the GUI and runs high rez full screen videos perfectly on YouTube or streaming from my server. I would love to see how my 4b would play videos, but it’s headless and I don’t wanna mess with it. My 4b is running on an SSD as well (I think that’s unnecessary but I found a cool case)