I have a Dell XPS 17 L702X laptop which is a Core i7 and supposed to be fast. I upgraded it to have 16 GB RAM. Still, the pain point was Disk I/O lag caused by HDD which came pre-installed. I decided to go for a swap of existing HDD with the fast Samsung 850 Evo 500 GB SSD as C: Drive and kept second HDD D: Drive the same. The results are there to see ! The below 2 screenshots before and after the upgrade tell their story. Windows Start is snappier and apps are snappier too ! Now I am pleased !