This book constitutes the refereed proceedings of the 8th European Performance Engineering Workshop, EPEW 2011, held in The English Lake District in October 2011. The  16 regular papers and 6 poster presentations papers presented together with 2 invited talks were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on performance-oriented design and analysis methods, model checking and validation, simulation techniques and experimental design, performability modelling and performance and power consumption tradeoffs.