This is an excellent question with no easy answer. Most cloud services are built for general purpose use. Vendors typically build infrastructure to attract a wide variety of customer application types. The service offered may not cater to a very high performance computing environment. There may be limitations on the customization of computing instances or the ability to supplement the existing environment. The best service providers offer a high performance virtualization layer with robust underlying computing and storage. If the provider can’t share what the platform is built on, it’s probably not going to provide high performance resources.