I had the same problem. Slow response to any command. If the software was working well beforehand, then started this all of a sudden, try the following:
Create a new project
Import your troubled project into the new project
Other tips:
make sure you have your project settings set to use your dedicated graphics card
make sure you have your graphics card settings set to adobe premiere cc
This all fixed my problem, but yes Premiere can be very buggy and mysterious on a pc or mac...
adobe premiere cc
hp pavilion dv7 i7 8gb ram
nvidia geforce gt 650m 2gb