Earlier this evening PC747 made a good and valid argument on why Root is dying. As these phones get higher speced and the software is tweaked we are finding less reasons to really NEED root. At this point if you are rooting you are doing so to either stick it to the man, or because you genuinely enjoy the mods you get from roms or xposed framework modules.
That being said their is still much that can be improved when it comes to OEM skins. Optimization is the main reason I still root and run custom roms. Developers dive into these stock roms and can clean them up and make them faster. "Arter97" has developed a custom kernel for the Note 5 that he says fixes memory management.
Last week I uploaded a quick speedtest which clearly shows that multitasking and memory management. The Note 5 ended up losing to an Iphone 6 because it had to totally shut down and reload every app. You should see your Note 5 pick up the speed a bit after applying the custom kernel found below.
via XDA