I've recently undated InDesign and it's become sluggish and unresponsive when doing anything from adding a new page to editing type.
I've trashed the prefs by holding, Shift, CTRL and Alt and I've got nothing else running. My iOS is fully up to date and I ran the update on Indesign today to 188.8.131.52
Anyone have any ideas? I've got loads of work to do and it's very frustrating.
Can you try and create a new user account on the machine for testing purposes?
Does it ever crash? .. if so you might want to gather the crash reports and call up Support so they can investigate.
In the meantime, if the first suggestion does not help, you can revert to CC 2014 to continue working at least for now, in the interest of time: