For great performance its best to have all media related files on a different drive then your system drive. At the very least a separate internal drive dedicated to media will do depending on the codec/format of the media you are editing.
For faster speed an external raid is really ideal. The more disks the more speed . You can get away with USB3 for some stuff.
I use a Dulce DQg2 raid system which is PCI-E based. Wonderful speed and performance.
The trick to getting PrP to sing is to keep it happy. What makes it happy are fast CPU(s), lots of ram, powerful graphics cards and fast media playback.
Im not familiar with GTech from first hand experience, but it sounds like a viable way to boost the speed of your media .
A more modern graphics card with enhanced CUDA will help when using certain effects, scaling images , frame rate adjustments, etc.
I would speculate the drive might be the biggest boost for your buck.
Tom Daigon
PrP / After Effects Editor
HP Z820 Dual 2687
64GB ram
Dulce DQg2 16TB raid
http://www.hdshotsandcuts.com