Photoshop CC(2015) 2015.0.1 is slow and laggy, even before anything is opened. File does not respond instantaneously, but lags, so do all the other menus. When a photo is opened many things slow down. Scrolling lags, the Spot Healing Brush will leave the Black circle, until I click somewhere else, sometimes. Nothing reacts as it has in the past with CS5 or CS6. I'm using a Mac Pro (Early 2008) 2 x 3 GHz Quad-Core Intel Xeon, 10GB/800 MHz DDR2 FB RAM, Version 10.10.5, ATI Radeon HD 2600 XT 26 MB RAM. I've set Photoshop preferences as suggested by a number of people with a similar problem, none of them helped. In Activity Monitor there is not a large amount of CPU nor Memory usage. There does not seem to be a lot of network activity when this happens. It's very frustrating.