[ppoulos]

I considered getting NUC5i5RYH NUC, but settled on D34010WYK NUC. So, if i3 performs well, i5 should easily. Have an i5-4570 laptop that does.

May be graphics driver issue. Are you on this driver?

Well I am happy (and somewhat embarrassed) to have found my problem. I also use an Atlona AT-UHD-SW-51 4K UHD 5 Input HDMI Switcher to switch multiple devices to one input in my Pioneer AVR. This is an expensive switcher I bought last year on Amazon, and it has run fairly well, but only recently seemed to be more flakey and unreliable in maintaining the integrity of a switched input. After I received my replacement NUC5i5RYH from Amazon, I noticed that the Atlona Switcher was reporting resolutions from the intel NUC that should not exist (4K60hz from the mini HDMI output, DVI resolutions, or plane crazy resolutions that the OLED display could not sync to). In desperation I did a repeat firmware update to the Atlona Switcher, with improvement, but it still started acting up.

When I tested my NUC without the switcher in line it performed just as good as others have reported - all 3D playback was impressive. 3D ISO file skipping is still frightfully slow, but reliable (as others have mentioned). After watching a 3D ISO Movie, 2D now plays fine without problems (with 3D switching off reliably). And 3D MKV playback is responsive and quick, but lip sync audio issues still exist on skipping chapters or time which can be fixed easily but reversing the video for a few seconds (again as others have reported). I am happy to report that the Intel NUC5i5RYH NUC is actually a very good machine except for a the two issues I have reported above.

Thanks for everyone's suggestions.