I usually praise the Mac Pro for its speed and build, but lately I am experiencing something which is really bothering me: When I initially turn it on, it has gotten quite slow at getting to the Apple logo on the screen. It easily takes 15-20 seconds before getting that far, and then it also takes a while to boot into Yosemite. There are a number of USB and Thunderbolt devices connected, but thinking back, they have always been there, and I am sure it used to be much faster. I have an external PCIe TB2 case, an external TB2 SSD, 2 ATDs, iPhones and iPads. Any suggestions? BTW - the Mac Pro will not boot at all if I connect my Solmeta GPS (for camera) via USB.