I just got back of holiday and plugged my external hdd (Iomega 500GB) and it backed up a few GB's but when i went to recover a file a few days ago time machine lagged. As soon as i opened it and it transitioned to the time machine screen the background was jumpy and it stopped and was smooth like it should be after about 10-15secs but as soon as i opened a folder it was jumpy again for a another 10-15secs? It's odd since it wasnt like this before i left?