I went from a 2010 iMac (i3 / 8GB / 5400 RPM drive) to the mini (i7 / 8GB / Fusion) and I notice a huge speed difference. The difference in speed is amazing. But that's probably a combination of the upgraded processor and switching to SSD. Solid state drives give even that crappiest of computers an amazing speed boost. The i7 processor is also very handy to me as I run VMware Fusion. My old iMac had problems with that.