Only at 1080p. 4K AV1 is a stutter fest for me on 2019 Nvidia Shield Pro, Roku Express 4K+ and Firestick 4K. It's only smooth playback on my N100 HTPC, and only the HTPC and Nvidia Shield can do surround sound through DLNA anyway.
Streaming sticks don't have the hardware to do 4K AV1 decoding though, or support surround sound streaming though DLNA shares. The gold standard for audio streaming has been the Nvidia Shield for many years but the hardware on that is too weak for 4K AV1 decoding as well. These days you have to...
The problem with these APUs is cost. $330+ APU + $250-300 ITX motherboard makes these things more expensive to buy than console, or even regular desktop parts and a discrete GPU. This is a far cry from the early AM4 days when you could spend $175 combined and get something like a 2200G/2400G and...
That would imply a 16GB 5080 at the price of the current 4090 with slightly more performance, which is just...ugh. But expected if AMD won't be doing anything other than midrange cards next gen.
Run Timespy Extreme. There's all kinds of factors that could cause a lower Timespy score that don't have anything to do with a "tired" RTX 4090 as the overall GPU load isn't very high.
This used to be an issue one some AMD systems because USB was fighting for bandwidth with PCI-E lanes and the solution was the reduce GPU PCI-E generation down one generation (i.e. from gen 4 to gen 3)
I prefer the sharpening effect of DLSS, so I usually turn it on if available compared to native resolution. However if DLAA is available at native resolution as an anti-aliasing option, I would take that over DLSS, since it doesn't tend to have the added graphical artifacts of DLSS.