Consider changing from Dalvik to ART (Android Run Time) in the Developer Settings. If you don't have the Developer Settings menu, go to Settings>About Phone, and tap Build Number 7 times in succession. Then go back to the main Settings menu, and you'll see Developer Settings. Go to that menu, turn on Developer Settings by flipping the switch at the upper right, then tap Select Runtime and pick ART. The phone will reboot, which will take about 10 minutes as all the apps are optimized for ART.
ART changes all apps to pre-compiled code, rather than the "just-in-time" compiling that gets done with traditional Android (which is how Dalvik works). Apps that run pre-compiled generally start and work a little faster.