1. A method of initializing a streaming application, the method comprising: receiving a source code that includes an operator graph, the operator graph including a plurality of processing elements for executing the streaming application, each processing element having one or more stream operators, wherein the streaming application is executed on one or more compute nodes, and wherein each compute node is adapted to execute the one or more stream operators; parsing, from the source code, a metadata tag describing a customization of at least one of the one or more stream operators having a windowing processing operation, wherein the customization is a delay operation within the windowing processing operation, wherein the customization changes from a first customization to a second customization in response to a change in central processing unit capacity on the one or more compute nodes, wherein the windowing procession operation includes one or more windows, and wherein the one or more windows are a logical container for tuples received by an input port of one of the one or more stream operators; and compiling the source code of the streaming application having the windowing processing operation, based on the metadata tag.