Hi there!

We are not sure why serving .SWF files would be slow. One possible theory could be that since .SWF is not the type Cassini knows about, cache control response headers are not generated, making the app feel somewhat sluggish under Cassini, compared to IIS.

If you wish to know what exactly is going on, consider running Fiddler tool - the HTTP interceptor - on the same machine as your browser. When running Fiddler, please be sure to use actual machine IP or host name instead of localhost or 127.0.0.1 in the browser's Address line. Using Fiddler you will be able to tell what happens when and how long it takes. You should be able to tell where exactly system slows down.

If you find that UltiDev Cassini does not do a good job serving files quickly, or if you simply want to ensure your content files are cached by the browser, consider taking the matter into your own hands and manually implementing IHttpHandler that will be associated with the file type in question and will serve files properly.

Please let us know if this information has helped.

Best regards,
UltiDev Team.