title: Why is rsync so slow?
body: <p>I use rsync to backup a folder of 60G between my laptop and an external USB drive. Only 4G of data have been added. It took a long time to finish : 2 hours.</p>
  
  <p>Here is the command :</p>
  
  <pre><code>rsync -av --exclude=target/ --exclude=".git/" --delete --link-dest=$destdir/backup.1 $element $destdir/backup.0
  </code></pre>
  
  <p>Do you have an explanation ?
  What slows down rsync more : a lot of small files or big binary files (photos) ?</p>