I get 16 hours under my Lenovo with ubuntu with tlp default settings. I have to be careful a bit with browsers (they use most in my workflow) but usually I just use lynx for programming searches. OS X on my MBP is ghastly: Apple replaced the battery and I use the same software as under Ubuntu but I struggle to get 3 hrs. On my Air it was wonderful. Windows I have not used for anything serious in 20 years.