Do you have fast startup turned on (http://www.tenforums.com/tutorials/4189-fast-startup-turn-off-windows-10-a.html) as if you do, that will account for resource usage at start up as win 10 loads everything that was open last time you shut down.
Win 10 doesn't shutdown when you turn it off, it uses Hybrid Hibernate and goes to sleep instead, saving half the data to memory and other half to hdd/ssd. The only time it actually turns off is during a restart. This speeds up boot times for people with HDD (normally) so its usually a good thing for hdd users, ssd don't see as much benefit since they can boot so fast anyway.
You can try turning it off and see if that reduces load at start up. Turning off fast start up will let PC turn off...