Start Flash Professional and open a FLA project file that has been built with Flash AS3 code.
Click the "Publish Settings" Option in the File menu, then click the Flash tab in the Publish Settings dialog box.
Click the Flash Player version in the Player list box for which you want to optimize the SWF file. Choose between different dated versions of Flash Player for desktop playback operation or smartphone playback operation.
Click from the Script text box the ActionScript 3 option to enable SWF publication of AS3-based Flash files (FLA files).
Change the setting of the JPEG-quality slider compression if your AS3 SWF flash file has bitmap images. Adjust the JPEG quality level to as close to 0 as possible to improve rendering speed and download time. Adjust the JPEG quality level to as close to 100 as possible to improve picture quality at the expense of rendering speed and download time.
Click the "Compress movie" check box to further reduce the download time required for your AS3 SWF file.
Click the "Set" button to adjust the sample rate and compression for all the sounds in the AS3 SWF. Adjust the sample rate and compression for each of the sounds in your file so that you minimize the size of the Flash SW and meet download time requirements. Adjust the sample and compression rate to improve the sound quality at the expense of increasing memory and download time requirements.
Click the "Protect from import" option to assign password protection to your Flash AS3 SWF file and prevent reverse engineering of your SWF file. Use the option to prevent the automated and pirated conversion of a SWF file to a FLA file (the original file you entered your Flash AS3 code, graphics and sound assets into). Type a password in the "Password" text field that others who want to use the SWF file must enter before using the SWF file.
Click "Publish" to make your AS3 SWF file.