I replace the 20W, 8-core C2750 Atom board in my Freenas some time ago for a 4-core C3558 one, as I felt is was a bit overkill in my setup with CPU load barely reaching 20%. In fact, FreeNas is actually having a very similar CPU load on the newer C3558 board.
So with the spare C2750 board I've sinse been testing it with Proxmox and I'm now running NextCloud (VM), PiHole (VM), Roon Server (VM), UniFi Controller (container), Hassio (VM) and Plex (container, no transcoding) very smoothly with a CPU load average between 10 and 40 percent. Enough processing power, but then I also have 32GB of ECC RAM. Roon is particularly sensitive and I've had problems with it in the past, but is now completely free from dropouts.
Almost all the apps I'm running can run on a Raspberry Pi and does not require a lot of CPU grunt. Especially as they are seldom, if ever, active simultaneously. I guess it also helps having enough RAM.
My goal was also to create a power efficient home system and I've so far been very happy with both performance and power consumption.