Ok, so reading the manual once again, It looks like I can press G to turn the light off. This gives a much better quick render view.

When I turn the light off in the main viewport, it seems like I can actually see my clone brush having an effect. But the lag and jump is truly terrible and unusable with mouse or tablet.

Windows 7, 64 bit, using the 64bit version of Blacksmith 3D 6.1.0.1

16GB ram

Intel Core 15-4670K 3.4 GHz (Not the greatest, but surely more than adequate?)

GeForce GTX 970 graphics card, which is one of the best around (cue flame warm)