If I have a site that will eventually have thousands of product images on it, would using image transforms slow things down?

2 Answers 2


Nope. Once a transform has been generated once, Craft remembers that, and saves it right in your asset source. Future page loads will get a direct URL to that generated image, so it gets loaded via your webserver (or S3, etc.) directly. No PHP involved.

  • Then you’ll start getting 404s on that image, since Craft won’t be aware that the file doesn’t exist anymore. You can always clear your craft_assettransformindex table though, which is where Craft stores its records of all generated transforms. Jun 15, 2014 at 3:46
  • What happens if that image got deleted?
    – carlcs
    Jun 15, 2014 at 3:52
  • Sorry I deleted that comment because I thought Brad made the race.. But then your very satisfying answer popped up :)
    – carlcs
    Jun 15, 2014 at 3:54
  • I just thought of something- what if Google PageSpeed has grabbed the images after the first time and is now serving them?
    – cmcjane
    Jun 16, 2014 at 12:46

For all practical purposes, no. The performance hit for images transforms happens the first time the transform is requested and generated. After that, the images are served as a normal file that your web server can serve up as quickly as any other file.

  • 2
    It's a Pixel & Tonic answer duel!
    – Lindsey D
    Jun 15, 2014 at 3:37
  • Just so we're clear here... I'm James T. Kirk.
    – Brad Bell
    Jun 15, 2014 at 3:39
  • What happens if that image got deleted?
    – carlcs
    Jun 15, 2014 at 3:40
  • In what context? The transformed image? The source image?
    – Brad Bell
    Jun 15, 2014 at 3:42
  • The transformed image is missing, does this trigger another transform? If yes, is there any script that initializes this and doesn't that take performance?
    – carlcs
    Jun 15, 2014 at 3:49

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