Hi there — I’m a new user to SPA myself, but I can tell you that an onboard SSD does run about 8-10x faster than external SSD drives, and as much as 40x the speed of an external HDD (non-SSD) drive. If your scratch disk is on a slower drive, that could certainly affect your performance. If you have a bunch of stuff on your internal drive, could you offload it to a backup drive so you have the fast storage available to Photoshop?
Angelo McComis
