Unity4 build initialization is very slow on Radeon HD7970

I have a problem with a build I made using Unity4 on a computer with TWO video cards and TWELVE displays (two DVI's and four DP's on each card). The CPU is a i7 Intel. I'm not using eyefinity. All displays are placed as single desktops. My OS is Windows 7.

When I start any build made with Unity4, the computer gets lazy. It takes minutes to start the process. But after initialization, everything gets normal.

Any idea in how to fix?