CM12 is good for battery life generally, but if the kernel isn't properly optimised for your device, you won't get much better perf/battery life.
Which is actually surprising on a Nex5, i'd have expected proper kernel support. When I was still using CM12, I would add a good 50% battery by underclocking and undervolting while choosing the right CPU Governor. it takes a lot of tinkering to get it right though.
CM12 is good for battery life generally, but if the kernel isn't properly optimised for your device, you won't get much better perf/battery life.
Which is actually surprising on a Nex5, i'd have expected proper kernel support. When I was still using CM12, I would add a good 50% battery by underclocking and undervolting while choosing the right CPU Governor. it takes a lot of tinkering to get it right though.