Dunno if anyone has posted this, but this is something new that I just learned. I went to my WiFi settings --> more -->advanced, and turned off "always allow scanning." I also changed the "keep wifi on during sleep" option to "only when plugged in."
The only problem with that, is when you shut off your screen, the WiFi will turn off unless plugged in. Although that may seem like a battery saver, it will also use LTE data for all the background tasks while the phone is asleep.
On another note (no pun intended), the one thing that irks me about Android phones as opposed to the iPhone. To me, I see an Android phone like owning a '60s muscle car. You're driving down the road and something just doesn't sound right. So you pull over and tune something in the engine.
With Android, it is like an endless cycle of tuning, since there is always something that doesn't feel right or hurting performance, just like my example above.
With an iPhone, and I've owned almost all of them, and random iOS bugs aside, you don't have to keep fine tuning it. Once you get it set up, it just works.
But with the Note 5, there is obviously a WiFi bug which is causing high battery drain when enabled. If I keep my WiFi off and just stay on LTE, but battery life is much better. But being on WiFi is supposed to increase batter life, not decrease it. I doubt Samsung will fix it on Lollipop, they are putting all their effort to release Marshmellow.
Oh, and my AT&T Note 5 is still on OJ1, whereas my Verizon Note 5 has been upgraded to OJ3 like a month ago.