I'm running DP 8.1 and of course dealing with the "Resuming..." problem. I deleted all the photos (backed up on OneDrive) and removed the photo app tile from the home screen and that alone has done this trick. Worth a try if you're dealing with the issue.
I tried since I don't really have many pictures and it didn't work for me.
Did you ever have the beta MS lock screen loaded? That is when I started getting the "resuming" delay. I removed it and did the whole kids corner thing. Still had the issue.
Loaded Awesome Lock sometime later and now I get a black screen delay (same time equivalent to the "resuming delay" maybe 3 seconds).
BTW I just lived with the resuming delay in-between until I loaded Awesome lock.