Not on a new one, but I changed to an SSD on my old 2006 iMac, and it definitely sped up startup and opening/closing documents. Not a night/day difference, but definitely noticeable. However, I'm now bugged that stuff I thought I could just store externally and use occasionally (iTunes songs, pictures) are not on the main machine. I would go for a Fusion drive, 3TB. More space, save money, should get most of the SSD benefit.