I just purchased a used mid 2011 iMac with only the factory installed 256Gb SSD. I have a 1 TB external in a nice firewire 800 enclosure. I can barely get all my files on the 256Gb SSD, but would like to put Maybe music and photos on the external HD to make more headspace on the SSD and plan for the future. I will be running Mavericks. Will putting photos and music on the external really slow down iPhoto or iTunes? What is the best way to organize the drive and files? Do I have to have the external up and running all the time or just when running iPhoto or iTunes? Thanks in advance.