I am looking for someone who can help to see if this is a problem with indesign or I am having bad luck with the 5k iMac. I ordered a 5K iMac with these specs:
24 gigs of ram (8 gigs Apple RAM, 16 gigs Kingston RAM)
AMD Radeon R9 M295X 4096 MB
I had graphic glitches in the display and incredibly poor performance with Indesign, Illustrator and Acrobat (all latest versions fully updated). Apple replaced the iMac. I was away over Christmas, so when I came back the new one was waiting for me. I began installing my apps yesterday prepping it so it can be production ready ASAP. I noticed right away that I was having the exact same problem I had with the last. I am hoping someone can do a test to see if they have the same results with Indesign and the upgrade GPU AMD Radeon R9 M295X 4096 MB.
My iMac has been in use for a month now and never shown trouble like that. But then I never used Mission Control or Spaces - until I tried it right now. Now I can confirm almost the same graphics errors, on the right margin in the minimized Mission Control view. Not as wide as yours, roughly covering the area of the scroll bar - I can still see most of the "split layout view" thingy bottom right. Correct me, if I resize the doc window to two thirds width, the bit smear intrudes further.
There was subtle change when I attached or detached an external monitor, some bit smear with desktop background would show in different stretches.
Regarding performance - Currently I do no heavy lifting in InDesign. Xcode compile times are really fast, as is the program start even in the debugger.
I noticed that Illustrator was a bit "jumpy" when scrolling, but blamed that on Illustrator.
System info: like yours, but 32 GB original Apple, Radeon R9 M295X 4096.