If you are running this in the a UI or the sequence editor I think I know what the problem might be, the UI or sequence editor will hold onto each execution your create, unless you make them hidden with tracing initially off or set them to close when completed.
1) to make the executions hidden with tracing initially off pass the following two constants bitwise OR'd together for the execution type mask parameter ExecTypeMask_TracingInitiallyOff | ExecTypeMask_InitiallyHidden
2) to make it close when done use the ExecTypeMask_CloseWindowWhenDone constant.
Hope this helps,
-Doug