Same issue here. Intel i7 4770k processor and Windows 7 64 SP1 (w/ latest updates).

Interesting results @Thomas Dinges (dingto). I was also wondering if it's a Windows related issue. Anyway, I disabled hair in the scene, set resolution at 50% and re-ran the test again:

I like the idea of showing quick tips on the splash screen. These can be good for both beginners and power users (eg. useful less used shorcuts, general info about certain 'hidden-gem' addons, general quick tips about improving usability, rendering, UI, etc etc). I'm sure you'll find an abundance of tips to keep things interesting and fresh for both beginner and advanced users.

Had the same issue with a project a while ago. Very long render times using Refraction. Just did @Zauber Paracelsus (zauberexonar)'s suggestion and yeah that seems to be the culprit.

It seems that the issue is with the Filter type under the texture's Image Sampling. By default, it's set to Box which produces sharp textures but in your file it's set to EWA which is more blurry. Not sure if the default was changed in 2.72 but you can always change it back to Box.