This isn't a request for assistance so much as it is a "user experience."
I've used LR for several years and feel quite competent with it for my uses - professional photography, stock photography, landscapes, and occasional weddings & portraits. I can't say that I've ever really had a problem with LR - until now. I also feel that my computer is pretty good - not the fastest machine, but plenty good - Mac OS X Yosemite; Mac Pro (early 2009); 3.46 GHz 6-core Intel Xeon; 32 GB ram; a couple of SSDs...
So, I installed LR CC through Creative Cloud and started using it on a project for which I'd been happily using LR 5.7 earlier in the day. Over the course of a couple of hours,
* LR crashed at least a half dozen times;
* When using the spot removal function, it's now very slow and laggy, as far as moving my working space around and doing the spot removal; and,
* Using the crop tool was also slow and laggy, meaning that I'd have to wait for the crop indicators to catch up to where I wanted them to be and then go back and correct them.
Very frustrating and not acceptable.
So, I've uninstalled LR CC and reinstalled LR 5.7.
Let me know when LR CC is "improved"...