I am having a similar problem. Boot up is fine, but I'm getting the spinning beach ball after almost every action. And I've got 16GB RAM on a fairly new machine (2013). This is driving me crazy.
Try restoring your InDesign preferences:
Also, go to About InDesign (InDesign menu on Mac, Help menu in Windows) and check your version. Make sure you're updated to 2015.2 (11.2) version.