Massive lag in program monitor on very fast computer??

This is driving my insane with Premiere pro,

I am experiencing a massive lag on most of the footage I use for editing on my computer. Stuttering, even at 1/4 resolution.

I am usually editing 4K R3D footage, My computer specs are as follows:

i7 Extreme 6950X Processor 3GHz (Clocked to 4Ghz) with Watercooling system

GTX Geforce 1080 8GB GDDR5 (had two in SLI but took one out as funnily enough that seemed to give me better performance)

64GB Ram DDR4 1TB SSD

32TB PROMISE Pegasus 2 R8 (where I usually edit from) with thunderbolt adapter (I benchmarked this and get around 300-400Mb/s)

I am using latest CC version of premiere pro. I have tried most things, enabling and disabling GPU acceleration, changing 3D settings, tweaking internal settings withing premiere pro.. etc.

Any and all advice would be massively appreciated.

I am pulling my hair out and this is my career.

Best,

Guillaume