Product and version:
FileMaker Pro Advanced Version 14.0.3
OS and version:
Mac OS X El Capitan 10.11.1
I have a solution that currently has around 200 custom styles contained within 3 separate themes and have noticed that FMPA will, over the course of the day, become more and more unresponsive to content loading into the 'Style' portion of the Inspector.
Because the Inspector loads object states every time you click on an object, this leads to FileMaker constantly pinwheeling while it loads the Styles into the Inspector. Eventually it gets so bad that it takes around 5-10 seconds just to click on any object within the solution.
Restarting FileMaker Pro Advanced instantly solves the issue. (At least for a few hours...)
How to replicate
Click on any object on a layout while in Layout Mode after FileMaker Pro Advanced has been open for more than 6 hours or so (at least in my solution...your results may vary)
Restart FileMaker Pro Advanced.