Flash MX 2004.
document.frameRate
Property; a float value that specifies the number of frames displayed per second when the SWF file plays; the default is 12. Setting this property is the same as setting the default frame rate in the Document Properties dialog box (Modify>Document) in the FLA file.
The following example sets the frame rate to 25.5 frames per second:
fl.getDocumentDOM().frameRate = 25.5;