You can make decisions as you design and deploy your Group Policy Objects (GPOs) that will have an impact on how quickly your Windows desktops start and become usable to your users. Some of these decisions are obvious, while many are not. This post will guide you through some of the ways Group Policy can impact performance as well as some of the improvements we made for Windows 8.
See the full post at http://blogs.technet.com/b/grouppolicy/archive/2013/05/23/group-policy-and-logon-impact.aspx.