Supervisory Control and Data Acquisition (SCADA) is a typical OT (Operational Technology) system that uses computers, networked data communications and graphical user interface for process supervisory management. SCADA systems are managing industrial processes or mission-critical infrastructure, and most installations are not making use of cloud-based infrastructure. In this paper, we present different scenarios for cloud-based SCADA and a framework for performance evaluation. Based on measurement results in different scenarios, we identify critical design issues, give recommendations how to address them, and demonstrate the general feasibility of cloud-based SCADA systems.