On my 4.4.4 phone, I use Xposed module BootManager by well known dev named defim. I like it for the nice simple interface. Sends a notification when you install an app that loads at boot. Of course be careful what you block.
One benefit-This reduces startup time after reboot.
Another benefit-SOME of those blocked apps will not load their service until you manually launch them.
But other blocked apps will auto launch a "running service" (takes precious high priority memory) some time later after boot, and some keep their running service loaded perpetually, even if there is no apparent need. There's not much way around that I'm afraid. (*). I just look very closely at the apps in this category and I'm more inclined to uninstall them.
* There is greenify, but that seems too gimicky for be. The app invents terms that don't exist elsewhere in the Android world (for starters "greenify", which they use as a verb)..that scares me away.
I don't know if xposed or boot manager is compatible with 5.0+