ISA Server 2004 Performance and Capacity planning Best Practices

Very often I get ask these kind of questions. Here you could find the Best Practices, for planning an ISA Server deployment with best performance and adequate capacity.
Microsoft Internet Security and Acceleration (ISA) Server 2004 provides controlled secure access between networks, and serves as a Web caching proxy providing fast Web response and offload capabilities. Its multi-layered architecture and advanced policy engine provide granular control of the balance between the level of security you need and the resources that are required. As an edge server connecting many networks, ISA Server handles large amounts of traffic compared to other servers in an organization. For this reason, it is built for high performance. This article provides guidelines for deploying ISA Server with best performance and adequate capacity.
(Link: https://www.microsoft.com/technet/prodtechnol/isa/2004/plan/bestpractices.mspx)