Cloud computing is a harbinger to a newer era in the field of computing where distributed and centralized services are used in a unique way. In cloud computing, the computational resources of different vendors and IT services providers are managed for providing an enormous and a scalable computing services platform that offers efficient data processing coupled with better QoS at a lower cost. The on-demand dynamic and scalable resource allocation is the main motif behind the development and deployment of cloud computing. The potential growth in this area and the presence of some dominant organizations with abundant resources (like Google, Amazon, Salesforce, Rackspace, Azure, GoGrid), make the field of cloud computing more fascinating. All the cloud computing processes need to be in unanimity to dole out better QoS i.e., to provide better software functionality, meet the tenant’s requirements for their desired processing power and to exploit elevated bandwidth.. However, several technical and functional e.g., pervasive access to resources, dynamic discovery, on the fly access and composition of resources pose serious challenges for cloud computing. In this study, the performance issues in cloud computing are discussed. A number of schemes pertaining to QoS issues are critically analyzed to point out their strengths and weaknesses. Some of the performance parameters at the three basic layers of the cloud — Infrastructure as a Service, Platform as a Service and Software as a Service — are also discussed in this paper.