Flash MP3 Player Efficiency

I am making a mp3 player in flash. When I click a file I am assuming it is loading into the users RAM right? Now if they click another song, and another song, do all these files remain in RAM or the browers cache, and will this cause the movie to slow down? If so, how would I script the player to terminate the loading the previous file and clear out the cache once another mp3 is clicked?