New versions of Android are great in that they tend to deliver some new features, both user-facing on the top layer as well as behind the scenes and under the hood. Android N will have a mixture of both, with optimized background performance being a key focus thanks to the improvements being made to Project Svelte through the JobScheduler API. More specifically, Google has made it so that Android N will be able to deliver better overall performance to the device user now that the JobScheduler API will optimize the times when apps need to make use of any certain actions which are relevant, like when Dropbox scans for network connectivity so it can backup your photos automatically.
Dropbox is not the only app which monitors your device for network changes, and for users who have more than a few apps which act in this way and continually attempt to request to receive the CONNECTIVITY_ACTION broadcast, performance as well as battery life can decrease due to multiple applications trying to wake up and connect to the network simultaneously to complete their tasks. With Android N, the JobScheduler API essentially makes it soo that applications are only notified of network connectivity and only receive a broadcast of the CONNECTIVITY_ACTION when the API determines it's the right time.
Basically, as the name of the API suggests, "JobScheduler" will set up a schedule for each app and tell it when it's ok to complete the actions they were set up to complete after receiving the broadcast for network connectivity. With a schedule set up, all apps won't be trying to access the network at the same time, nor will apps wake up all at once whenever network changes are made (like moving between WiFi and cellular network connections), so things should perform quite a bit better and battery life should have a small improvement as well, and this is in addition to the changes Google has made to Doze Mode for better battery life. Granted, with the background performance optimizations in Project Svelte, this is a change that uses aren't going to visually be aware of, but they should notice the performance boost of their device and they should see a slight uptick in battery life thanks to this particular under the hood tweak.