How Should Google Make Project Roadrunner?

Everybody knows battery life on Android has improved substantially but it's still not perfect and OEMs seem to be brute forcing it through larger batteries. Google should do something on the software side like it did for project butter. Hopefully it can be a key feature of KLP.

I have a few ideas.

Immediately underclock the processor once the screen is off.

Slow down background processes so the CPU doesn't have to work as hard.

Power down (not power off) the wireless radios when the screen is off. LTE uses 2 antennas. Why not turn off one?

Group notifications into 15 minute intervals. Only do real push for those the user specifies in the settings. Having multiple constant connections is a waste.

When something is swiped off recent apps, it should kill the task entirely.

Widgets should not be constantly polling anything. Only poll when the widget is on screen.

What do you think Google could do?