The reason is in chrome the background tabs don't get frozen and stop executing etc...
Safari has had a huge makeover to improve the amount of energy use for things like background tabs/etc.... Or even not running when occluded by another window. Small things like that add up overall.
I think this is the way forward for improving the efficiency of our software in general. I'm glad someone is bringing power use to light alongside cpu/memory/disk/network.
As for the os level stuff, have you tested the actual time under use or just looked at the estimates?
I'm noticing the same as well with my retina actually.
The power drain differences are significant enough for me to swap back to safari.
I was getting ~7 hoursish (hard to tell I tend to compile/browse/etc) before and now it looks more like 5. Which is disappointing to be honest. Though using non "best for retina" seems to kick in the discreet gpu more often now.
Safari has had a huge makeover to improve the amount of energy use for things like background tabs/etc.... Or even not running when occluded by another window. Small things like that add up overall.
I think this is the way forward for improving the efficiency of our software in general. I'm glad someone is bringing power use to light alongside cpu/memory/disk/network.
As for the os level stuff, have you tested the actual time under use or just looked at the estimates?