SWTOR uses about up to 8Gb of data (provided you have high settings) continuously. And it's limited to 2.5Gb used at the same time. So it loads in and out of those 2.5Gb data continuously. When it comes to frames per second, the impact is huge. It's a lot faster to do this from RAM to RAM than from SSD to RAM. RAM will deliver the data nearly instantaneously whereas it'll take a few ms for your SSD to do it. Check the FPS drops in PVP or crowded areas with classic HD, SSD, HD+unleashed, SSD+unleashed. Results are self explanatory.