Audio dropouts in liveset

[tigali]

So I'm putting together a live set of about 8 of my tracks broken down into mostly audio clips with one Kit that I play live with a pad controller and one 3rd party plugin synth that I play live with a separate keyboard controller (Monark is the synth). I'm doing some rehearsals at the moment and I'm experiencing audio dropouts of less than a second but it's too big a deal to be able to take out live. Any ideas why I'm getting them? All the relevant specs below:
CPU running at 30% resting rising to about 40% when everythings playing
MacBookPro with 2.53GHz Core 2 Duo with 4GB of RAM running OSX 10.9.5
Live version 9.1.6
Audio interface is a Focusrite Forte

Can't think of anything else that would be relevant right now. Obviously I can't be having dropouts in mid flow of a live show so I really need this fixed.
Thanks.

[siliconarc]

turned off wifi? i get hickups in audio when there's network activity.

[chapelier fou]

Disk access light flashing ?