The LNCS journal Transactions on Computational Science reflects recent developments in the field of Computational Science, conceiving the field not as a mere ancillary science but rather as aninnovative approach supporting many other scientific disciplines. The journalfocuses on original high-quality research in the realm of computational sciencein parallel and distributed environments, encompassing the facilitatingtheoretical foundations and the applications of large-scale computations and massivedata processing. It addresses researchers and practitioners in areas rangingfrom aerospace to biochemistry, from electronics to geosciences, frommathematics to software architecture, presenting verifiable computationalmethods, findings, and solutions, and enabling industrial users to applytechniques of leading-edge, large-scale, high performance computationalmethods.This, the 27th issue of the Transactions on Computational Science journal, is devoted to the topic ofhigh-performancecomputing. It contains eight full papers, covering the areas of cloudmiddleware, multi-processor systems, quantum computing, optimization, andsecure biometric-based encryption methods.