One of the most time intensive task in Lightroom is generating and/or dealing with the previews. So how do you speed up the previews generation? You can clean up and defragment your drive: ‘Start’ > ‘All Programs` > ‘Accessories’ > ‘System tools’ > ‘Disk Cleanup’ and ‘Disk Defragmenter’.

This is mostly due to what’s called “file fragmentation”, and that’s where Windows and OSx part ways. Windows will use the first space available on the hard drive whether it’s big enough or not, and write the next fragment to the next available spot and so on… OSx first looks for the first available spot that’s big enough and write it there. If there’s no spot spot large enough, then it will split the file in the available spots.

The problem becomes awful with Lightroom when it generates the full previews.

Fragmented Defragmented
Generate 1152 1:1 Previews 1hr 52mn 1hr 3mn

Note that this also includes both the import and generating the preview. The defragmented timing was done after a reboot.

  • You need to make sure that you have at a minimum of least 15% of free disk space. I usually declare a drive full when there’s only 33% disk space free left.
  • To defragment, I use now the FREE Auslogics. It works with Windows: 7/2008/Vista/2003/XP (32-bit & 64-bit).
  • I need to run the full defrag 3 to 5 times to fully defragment my drive.
  • For OSx, you can search for a disk defragmenter at: CNet but I can’t make a recommendation since I do not operate a Mac.