Book excerpt: This IBM® RedpaperTM is the second in a series that addresses the performance and capacity considerations of the evolving cloud computing model. The first Redpaper publication (Performance Implications of Cloud Computing, REDP-4875) introduced cloud computing with its various deployment models, support roles, and offerings along with IT performance and capacity implications associated with these deployment models and offerings. In this redpaper, we discuss lessons learned in the two years since the first paper was written. We offer practical guidance about how to select workloads that work best with cloud computing, and about how to address areas, such as performance testing, monitoring, service level agreements, and capacity planning considerations for both single and multi-tenancy environments. We also provide an example of a recent project where cloud computing solved current business needs (such as cost reduction, optimization of infrastructure utilization, and more efficient systems management and reporting capabilities) and how the solution addressed performance and capacity challenges. We conclude with a summary of the lessons learned and a perspective about how cloud computing can affect performance and capacity in the future.