R – sifr3 line height issue

Check whether the extra size is inside the Flash movie, or around it. In the latter case, you'll have to resort to CSS tweaking.

In the former case, check out the tuneHeight / tuneWidth and offsetTop / offsetLeft arguments for sIFR.replace(). These let you change position of the text inside the Flash movie and let you change how much margin the Flash movie leaves around the text.

This is sometimes necessary because the dimensions of the text are reported incorrectly by Flash.

Fundamentally, this is an issue between the browser and the Flash player. As sIFR inserts the Flash movies into the page, the browser initializes the Flash plugin with the path to the Flash movie. If the movie is not yet in a local cache, it's requested from the server. Since the movies are inserted within a few milliseconds, this would mean that a request is made for each inserted movie.

sIFR tries to prevent this by prefetching the Flash movies. It does this ones per browser session, based on a session cookie. This merely fires off a request for the movie file, and hopefully that file is in the cache by the time replacement starts. Therefore its important to load the sIFR JavaScript code as early as possible, and to activate sIFR properly by passing the Flash movies to the sIFR.activate() method.

In my experience the only way to reliably test this process is clearing browser cache, closing all browser instances (to get rid of the session cookie), then opening the browser and going straight to the page you want to test. I don't find the activity monitors within browsers reliable, so either check through an HTTP proxy or the server logs.

The one remaining improvement I could make is to try and detect the progress of the prefetch, and hold off on replacing elements until the prefetch is complete.