MacBook Pro, 500GB HD - on an overseas trip I filled the Hard Disk to near capacity with photos, leaving about 40GB remaining. Understandably the Mac was a little sluggish at startup, and also noticed slow response in apps such as browsers (Firefox, Safari, Chrome), e.g. after typing some letters, it would take a few seconds before the letters would appear on screen. Upon returning home from the trip, I transferred all the photos off the Hard Disk such that there is now 265GB free, i.e. around 55% of the Hard Disk is now empty. However, the sluggish response remains - mostly when I just start up a browser. e.g. it might take 8 seconds for the letters to appear in the browser field. Sometimes when I press the delete button, there is a similar time lag. This time lag disappears after a few minutes. e.g. when I started up Chrome browser, it took 8 seconds for the words www.macrumors.com to appear in the URL field, but now, as I typing this the there is no time lag. Any comments?