AE CS6 very slow with footage

Hi guys,

I am using AE Effects CS6 (11.0.4.2) on a new Macbook Pro with these specs:

2.8 GHz Intel Core i5

16 GB MHz DDR3

Intel Iris 1536 MB

The problem I am having is that when imported footage is visible as footage or a layer, AE becomes very slow with every click of the mouse on either the timeline or the footage in the viewer itself causing the color wheel to appear, often for 30 seconds at a time. Strangely, dealing with the composition has no issues.

Any ideas guys?

Thanks in advance