I'm having this problem in Indesign and Illustrator.
Running the most recent updates of CC 2015 on Yosemite 10.10.5.
Is it possible to get an answer about this?
My problem was the CC library. View your CC library in inDesign and if there is a problem loading it then that's why it lags.
Adobe gave me this link and it solved my problem.
Could you please perform the steps mentioned on the following wiki
to enable CC library panel.
Once I did this everything was back to normal. Since then it has happened a few times but this process always fixes it.
YOU ARE MY HERO!!!! Thanks!
am merely the messenger of Adobe customer service awesomeness. Glad I could help