Photoshop CC customer running windows 7 professional on work station Dell. When I open menu items like "curves" the dialog box takes several seconds to draw and be visible. any idea why so slow??

We can't know. You have not provided exact system information or details like what the prefs for hardware acceleration look like, what color profiles are used, what peripherals and so on. From simple graphics issues to a flaky driver for a tablet this could be anything.

Mylenium