I'm having a serious problem where placed images, no matter their size, are extreamly slow to render. This happens no matter the display preference (High Quality or Typical). Scrolling through a document causes InDesign to continuously churn and beachball. This happens when scrolling up and down through a single page, moving through different pages and even when moving elements around on a page. It appears to be re-rendering everything with each move.
I've restarted InDesign. Restarted my machine (Mac Pro - Late 2013, running 10.11.6, with a new Thunderbolt display). I've uninstalled and reinstalled InDesign. And, because I can not stop working, I've moved to an older machine, running CC 2014.2, and I am working with the same file with no problems.
Now, here's curve ball. If I click out of InDesign, say to the finder, I can hover over the InDesign document, without going into it, and scroll through the pages perfectly. Hi-res and all. As soon as I click back into InDesign, the re-rendering happens.