We've got an app written in Flex that displays data from our app. The .swf file is only 427kb, but it takes a full five seconds to load in Firefox. This is a headache for our users because they need to access the page that contains the app frequently. (The app displays documents, and it's really slow to march through a list of them).

I've confirmed that it's not a slow web server problem. The .swf appears to be cached in the browser. Firebug reports that every time the web page accesses the .swf, the app server returns a "304 Not Modified" response, meaning that the load time from the server is almost zero.

Is there anything we can do to debug this issue? Or is the Flash player just slow?