Grid workflows for e-science are complex and prone to failures. However, there is a lack of performance monitoring and analysis tools for supporting the user as well as workflow middleware to monitor and understand the performance of complex interactions among Grid applications, middleware and resources involved in workflow executions. In this paper, we present a novel integrated environment which supports online performance monitoring and analysis of service-oriented workflows. Performance monitoring and analysis of Grid workflows and infrastructure is conducted through a Web portal. Performance overheads of Grid workflows are analyzed in a systematic way, and performance problems can be detected during runtime. Moreover, we present several languages that alleviate the interaction among performance monitoring and analysis services and their clients. Our system has been integrated into the K-WfGrid knowledge-based workflow system. It plays a key role in supporting the user and developer to analyze their workflows and in providing performance knowledge for constructing and executing workflows.