Technote

The Request/Response Capture feature uses high-speed split stream technology in order to ensure that the body and headers are written with the minimum of overhead to your application. When a J2EE application opens the request or response body, the Request/Response Capture module immediately splits the stream and opens a file for the capture. FusionReactor does not perform any CPU-expensive tests to determine whether data is flowing in the stream first. The files are simply a sign that the J2EE application opened the stream but did not read from or write to it.