Hi! I just got my late iMac 5k with 2TB fusion a few days ago. For internet browsing and coding, it works great. I finally installed Lightroom and Photoshop today and I'm having delay/stall issue whenever I close either of them or change tab to tab in the application. When I run disk speed performance, I get 316 write and 885 read. It's actually faster than my early 2013 Macbook Pro retina. I'm not sure where this stall/delay comes from... If I'm okay with slower performance of SSD, should I change to external SSD instead?