I recently bought Infuse Pro and it works like a charm on the Apple TV 4. I access my content (mkv) via SMB shares from a mini PC with a few external hard drives attached. The Apple TV is wired to the LAN and seems to play everything I throw at it without a hitch.
Many thanks to the developers for the capable app, which of course is a giant step up from the built-in media player in our smart-TV.
I also tried the iPad version, and first I must say that I am relieved to read that a library view is in the works also for the iOS version given our setup with several shares explained above.
I have only tried a few files on our trusty old iPad 3, but both 720p and 1080p (with standard bitrates I guess) lags/stutters.
Before I start trouble shooting our wireless network, is there a lower limit on what iPad model is required to decode the files? Since there is no server component (like Plex for example), I guess the CPU in the iPad must play a part in this?