After the last update, I've been experiencing horrible slowdowns between tabs, specially while cropping. Never had that with my old catalogs.
I created a new one with about 200 pics and its taking ages to crop and angle.
First CPU peak is switching tabs. Second is clicking crop & straighten. The rest is the time I have to wait between clicking "Crop & Straighten" and the mouse actually responds.
Running on a Macbook Pro 15" Retina, 16GB RAM, 256GB SSD, Intel 2.3Ghz Core i7. The RAW images are not even max resolution, only "Small Raw" from a 5D Mk2.
Installed LR5 three weeks ago. Used LR3 for ages, not a single problem.
Lets see if it gets better with the update