Recommended affordable hardware for 4k video playback?

[T. Zack Crawford]

I have historically just hooked up an old laptop to my TV to watch movies and such, but I recently upgraded to 4k and my poor 4x1.5 GHz CPU (AMD E2-6110) can't seem to keep up. Realistically, it kind of struggled with 1080p to begin with. I have tinkered with mpv hardware decoding options and vaapi, but I'm thinking my old boy with the weak cpu and integrated graphics just isn't capable. Pretty sure that's the issue, I don't have any major background processes running and it's probably not a buffering issue considering that in this case I'm playing videos stored on an internal 1TB SSD and I have 8GB RAM. VLC is probably working worse than mpv.

Any recommendations for a cheap hardware upgrade for this? Thinking I might just try to find an old used computer with some kind of GPU. Likely a raspberry pi would have the same problem? What should I be considering for minimum/recommended specs? Would puppy linux or some kind of dedicated OS be better than a standard arch linux/i3 setup? I feel like what I currently run is about as snappy as the device will get.