Optimizing is an important step to keeping your files animating correctly and manageable for download (if they are for the web). Intensive frame by frame animation slows down the frame rate of your animation. Excessive tweening and alpha usage will also slow down your frame rate Excessive use of bitmaps, gradients, alphas, and soften edges can also slow down the playback of your file. Make sure these are compressed and used only when necessary.

To get the best performance possible

1. optimize curves for complex shapes.

2. Cut off excess unused portions of audio from sound files in Flash.

3. Using symbols again and again for everything in your movie decreases file size, but sometimes it can slow down frame rate if it is used excessively in one frame (100's of the same symbol). Break a background apart and group it instead. Sometimes this reduces the size of bitmaps as well (breaking apart and grouping them).

Reusing symbols is the most important part of optimization. Double check your symbol usage and make sure that everything possible is a symbol and reused. Delete unnecessary items from the library to make the fla file smaller (this has no effect on your published movie, but it keeps the project file small and easier to work in).

Use save as to save your file every so often reduces the file size.

4. Preload your movie, just in case a user has a slower connection, and test the speed of your preloader on different connections (both in the Flash authoring environment and on a real dial-up connection from a server). Use the bandwidth profiler to check the loading.

5. Publish the size report with your movie and look for unusually large symbols, audio, or bitmaps (remake them to make them smaller if necessary).

6. Adjust sound and JPG compression in the publish settings of your movie, under File>Publish Settings