IT support organizations are in charge of restoring normal operations after IT service disruptions, among other tasks. Such organizations can be complex systems, with a large network of interacting support groups subject to complex management policies. The performance assessment and optimization of IT support organizations is an extremely challenging task that requires considering organization-specific structure, behavior, and business-level objectives. This paper presents Symian-Web, a decision support tool that enables IT managers to both assess and improve IT support organization performance by using what-if scenario analysis. Symian-Web features advanced information visualization concepts and metaphors, allowing for precise and timely assessment of IT support organization performance, and facilitating their redesign. Symian-Web is realized as a cloud computing-based Web application, thus enabling the tool to take advantage of the ondemand computational capabilities provided by the cloud.