Why does the loading indicator stays on the screen for an extended period when memory card are inserted?

When Memory Stick PRO Duo™ media or SD memory card is inserted in the Reader, the loading indicator will display until the Reader indexes all compatible files on the memory media. As the number of files on the memory card increases, the amount of time required to index the files will increase. To reduce the Reader's indexing time, reduce the number of files on the memory media.