1. A computer-implemented method executed by at least one processor for managing a streaming application, the method comprising: executing a streaming application that comprises a flow graph that includes a plurality of operators that process a plurality of data tuples; monitoring performance of the streaming application; when performance of the streaming application needs to be improved, requesting a cloud manager to provision at least one virtual machine with logic to implement at least one of the plurality of operators; after the cloud manager provisions the at least one virtual machine, modifying the flow graph to include the at least one virtual machine in the flow graph of the streaming application; and when performance of the streaming application no longer needs to be improved, keeping the at least one virtual machine in a ready state until the at least one virtual machine is needed to implement at least one of the plurality of operators, wherein the ready state comprises a first state where each of the at least one virtual machine is running with an input and an output of an operator implemented by the virtual machine disconnected from the flow graph.