It's been a while! But I'm still happy with my decision to go with an air almost 4 years ago. I have a 13' 2013 air, 8GB ram and running an i5 processor. Anyway... I've noticed that my battery life on my air has significantly drop prior to being on mountain lion. I could usually get at least 9 hours of internet use on a full charge, but ever since I upgraded to El Capitan 4 months ago (since some programs/apps no longer supported or began to stop supporting mountain lion) my air on a full charge, indicates ~7 hours of battery life. -I keep my brightness at the 7th/8th level and I keep Bluetooth off when not in use. Is there any tips for this? My friend told me to update to sierra, but I feel like that would make it worse. I'm also thinking about upgrading to a macbook pro 2015 since it seems like an optimal time as I'm not digging what apples doing with the newer pros, or should I wait?