After reading a few reviews about the Haswell CPU series, I concluded that upgrading from Ivy or Sandy bridge might not be worth it considering the limited power gain. However Intel does advertise that the power efficiency has increased dramatically compared to the previous editions of CPUs.
I'm wondering how this translates to practical usage as there is little I can find about that. How does a notebook equiped with a Hasswell CPU perform in real life compared to its predecesor when it comes to power usage? Are we talking a few minutes of extra battery time per hour (during normal usage) or are there significant gains?
I do not wish to debate, I prefer facts and numbers.