Currently my MiBox is on Wifi and PC on ethernet, I'm thinking of running a wire so I can get my MiBox on Ethernet, but the only reason I'd want that super fast connection is for game streaming, I get a little bit of lag over Wifi, its noticable but its playable, just wondering if direct ethernet will make it better/worth it?
Wired will undoubtedly be better for it's stability and speed. I can't give you hard numbers though.
It may or may not be worth it depending on how involved it is to run the cable properly. I'd try connecting them with a long cable running across the floor and see how it operates before cutting any holes in the wall.
The Mi Box is capped at 100 Mbps over wired Ethernet. Streaming 4K encoded in HEVC at 24 fps consumes about 40 Mbps.
I streamed Witcher 3 to my Mi Box using Moonlight and was able to keep up 1080p/60fps without any hiccups or noticable input lag.
Check some prior posts to find acceptable USB-Ethernet dongles to be used with your MiBox. Its hit or miss just buying one off the shelf without any confirmation of reliability.
What's your WiFi network? If you're running ac I can't imagine you're going to see much improvement. I'd say you'd need mu-mimo but with the PC wired that won't even matter.
On a solid WiFi router your devices should be getting a few hundred mbps no problem internally. Hell, my outbound is 350+. Never done an internal test but you don't need anywhere near that to stream a game in 720/1080
Maybe. I know nothing of your network setup or environment that it operates in, but going wired won't hurt anything.