Pro Tools 12 - Very Slow - Brand New iMac Retina

Hello,

Having trouble with Pro Tools 12 on my new iMac. I feel it can't keep up with my speed, which has never been the case. I'll hit Command R to T to zoom in and out and it sometimes takes a second or 2 to register. Can someone please help me?

Thanks

Here are the specs:

iMac (Retina 5K, 27 inch, Late 2014)
OS X Yosemite 10.10.10
Processor 3.5Ghz Intel Core i5
Memory 16GB 1600 MHz DDR3
Startup Disk Macintosh HD
Graphics AMD Radeon R9 M290X 2048MB