If you use Aperture 3 this new software update should prove very useful for you as it is claimed that it improves overall stability and fixes issues in a number of areas ..

  • It addresses stability when using the Retouch brush on large images.
  • It addresses issues related to Chromatic Aberration adjustment quality.
  • It fixes several issues relevant to the viewing, adding, altering and removing detected faces.
  • It rectifies several issues to do with printing
  • It rectifies thumbnail issues and improves reliability with many Library issues

plus much more.

For more detailed information on this update, please visit  http://support.apple.com/kb/TS2518