To correct a previous statement.

If your frame rates are limited by texture lag a SSD will help. Stand in org somewhere where a lot of new characters won't be coming in and out of visual range and spin, this will stress your gpu but not the drive.

If you get high frame rates spinning but then get low frame rates when you run through org (with new characters coming in and out of range) you need an SSD.

If you get low frame rates spinning you need a better gpu.