In an interview with EDGE, Jonathan Blow talked about performance on PS4 vs. PC on his upcoming game The Witness, and he said "the equivalent game will run faster" on PS4. I'm not really sure what that means, but the context is after the jump.
"For The Witness we're mostly interested in the base machine and how fast it is - the fact it has faster RAM than a PC."
Indeed, the PS4 will have 8GB of GDDR5 RAM, while your regular high-end PC only has DDR3 RAM. But the comparison is about more than just RAM speed.
"[RAM] really helps in shuttling graphics resources around, and since it's not running a heavyweight operating system like Windows that gets in the way of your graphics. Rendering stuff through Windows has an impact on performance. Since a console is just about games, that doesn't happen, and the equivalent game will run faster. And if you can target to specific hardware you can make it run faster, too."