Black Viper
He has an excellent Services guide. Services are programs which run in the background, slowing the pc down. Many of these are not needed.
Be aware that this list is no longer updated. Windows is working more and more efficiently so tweaking the OS is not necessary any longer.
Tweakhound
This site contains the best guide to tweak windows 10. It's all very well explained. A must read!
Axcel216
It's a very good site to find information on tweaking windows.
Stop MS spying
O&0 shut up 10 stops all sorts of information from you being sent to Microsoft.
Note: How to stop Windows 10 to spy on you.
NTlite
Gives you the option to build a windows image with the features and programs you want to be included on the windows image.