The ability to range a web application or website is tied directly to understanding where the resource constraints lie and what force the addition of various resources has on the Multi-Tenant applications. Unfortunately, the skeleton and architects more often than not assume that simply adding another server into the mix can fix any performance difficulty and security issues as well as data storage issues. When we start adding new hardware/update existing hardware in a private, public, Hybrid clouds, the complexity starts growing which affects recital and hence security. While priced cloud computing services save pains to maintain the computational environment, there are several drawbacks such as overhead of virtual machines, possibility to share one physical machine with several virtual machines, and indeterminacy of topological allocation of their own virtual machines. Multi-tenancy is one of key characteristics of the service oriented computing especially for Software as a Service (SaaS) to leverage economy of scale to drive down total cost of ownership for both service consumer and provider. This paper aims to study the technologies to build a cost-effective, protected and scalable multi-tenant infrastructure and how to improve the security and enhance its performance. This paper also identifies the potential performance bottlenecks, summarizes corresponding optimization approaches and best implementation practices for different multi-tenant business usage models