I have about 230,000 images in my catalog, and nearly all Library operations are painfully slow. For example, if I select All Images, and click on the Metdata filter, it takes approximately 30 seconds for LR to draw the 4 menus at the top of the screen - Date, Cmera, Lens, and Label. I've wondered whether this is because of the size of my catalog.
I'm running LR CC under Windows 10, with the application on an SSD, my catalog on an SSD, and my images on a few spinning hard drives. I have 16GB of memory, and Cor i7 3770.