Latest firmware on everything, of course.
Just picked up a used KM85c but this applies to UMD-K8500 as well. Identical units.
Experienced the 3-4 sec blank screen thing on an old non bluray dvd so did reset and that cured it.
Still experienced 2-3 sec response delay when, for example, clicking the remote's FF arrow to go to next track.
Also experienced 2-3 sec lip sync delay after hitting play/pause, and then play/pause again to restart play.
Discovered that if I do reset and DO NOT ACCEPT SMART HUB
- that is I do not check the accept box, but choose next arrow and choose skip.(resulting home screen only diff is no apps)(may need to power off and power on to get it)(can then access settings, but I leave everything at defaults.)
ALL THESE PROBLEMS WENT AWAY.
Now get virtually instantaneous response.
I have seen similar reported delays on a 9700 so probably applies to all Samsung blu-ray players.
This is no prob for me since I use my 4K Roku Premiere+ (4630X) to do all my streaming.
"reset" here means press square stop button on player unit (NOT remote) and hold for 8 sec and it will start to go through the reset cycle - takes a minute or so - be patient!!!
Darn fine BR 4K/HDR player for $75!!!
TV is new Vizio V436-G1 w HDR10
HDMI cables are $15 Monster 21Gig.
Audio is optical from TV to LG soundbar.
I have posted this discovery on the sammy forums.