Settings to help speed up Windows 10

Delivery Optimization
Settings > Update & security > Advanced options > Allow downloads from other PCs
(turn this off)

Notifications
Settings > System > Notifications & actions   Turn off all 5 "Notifications" items.

Start Menu Ads
Settings > Personalization > Start > Show suggestions occasionally in Start
(turn this off)

Targeted ads from third-party apps
Settings > Privacy > General (Change privacy options) Turn all four items off.

Cortana (getting to know you)
Settings > Privacy > Speech, inking, & typing and clicking Stop getting to know me.

Background Apps
Settings > Privacy > Background apps  (Turn off all the apps you want to or turn off "Let apps run in the background".)

Syncing
Settings > Accounts > Sync your settings   Turn this off.  If your account is a local account this will already be off.

Visual Interface
Settings > Type "Performance" in the search box, and pick "Adjust the appearance and Performance of Windows".
Uncheck all the visual effects you'd prefer not to see.  Or pick one of the "Adjust" options above the list.