My Lightroom catalog right now is only about 25 K images, but I have a big backlog of images to import. And then I need to scan years of slides. Within a year, I expect to have about 60-80 K images in the catalog. I've read about people with Lightroom catalogs of 500 K images! So I do what you do: Keep the catalog on an SSD and all the image files on a 7200 rpm HDD (Hitachi, of course). My current desktop is about 8 years old, ASUS P9X79Pro with an Intel 3930K. I'm planning to upgrade either later this year or early next year, after all the recently announced motherboards have started to ship.