Usability Tip 7 from Adobe:
Target Low-Bandwidth Users
The smaller the download, the better. The initial screen download should be no more than 40k, including all Adobe Flash files, HTML, and images.
To reduce download time, use smaller vector-based images (unless the image is a complex bitmap, in which case it's better left as a bitmap file), and use the Load Movie action only when the user specifically requests a file.
If a wait is unavoidable, provide a load time sequence with a progress indicator, and have navigation load in the first 5 seconds whenever possible.
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