Title: [Plugin: Regenerate Thumbnails] CPU usage
Last modified: August 19, 2016

---

# [Plugin: Regenerate Thumbnails] CPU usage

 *  [Dev93](https://wordpress.org/support/users/dev93/)
 * (@dev93)
 * [15 years, 9 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/)
 * Hi there,
 * I have been having some CPU usage issues with my host server from using a theme
   that has TimThumb, creates thumbnails on the fly.
 * I want to know how Regenerate Thumbnails works. Right now I have to work around
   TimThumb with ‘set featured images’ but it is not a perfect fix.
 * I am hoping this one might. Any help is really appreciated.
    devin

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Plugin Contributor [viper007bond](https://wordpress.org/support/users/viper007bond/)
 * (@viper007bond)
 * [15 years, 9 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1629657)
 * When you upload an image to WordPress using the built-in uploader, thumbnail 
   files are created in the upload directory at the sizes specified at Settings -
   > Media as well as any custom sizes defined in your theme (if it does this).
 * If you change the dimensions at Settings -> Media or add a new custom thumbnail
   size (via theme switch or theme editing), you can use Regenerate Thumbnails to
   go through and re-thumbnail all of your uploaded images.
 * It’ll cause a lot of CPU usage obviously, but it’s only a one-time process.
 *  Thread Starter [Dev93](https://wordpress.org/support/users/dev93/)
 * (@dev93)
 * [15 years, 9 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1629753)
 * Thanks Alex,
 * I will try playing with it on a smaller site first.
 * Best,
    devin
 *  Plugin Contributor [viper007bond](https://wordpress.org/support/users/viper007bond/)
 * (@viper007bond)
 * [15 years, 9 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1629764)
 * I’m not 100% sure it skips thumbnails if they already exist at the correct size.
   I need to tweak this plugin a bit. 🙂
 *  [pantsonhead](https://wordpress.org/support/users/pantsonhead/)
 * (@pantsonhead)
 * [15 years, 6 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1630013)
 * wp_generate_attachment_metadata() currently does not skip thumbnails if they 
   already exist. This is definitely worth bearing in mind if you have extra custom
   image sizes or a large volume or images as ALL image sizes are reprocessed which
   can take a very long time.
 * I altered my copy of the plugin to check if the file for each image size already
   exists and only generate those required. Tests suggests this reduced the processing
   time by about 70%.
 *  Plugin Contributor [viper007bond](https://wordpress.org/support/users/viper007bond/)
 * (@viper007bond)
 * [15 years, 6 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1630014)
 * Thanks for the reminder about this. I completely forgot. 🙂

Viewing 5 replies - 1 through 5 (of 5 total)

The topic ‘[Plugin: Regenerate Thumbnails] CPU usage’ is closed to new replies.

 * ![](https://ps.w.org/regenerate-thumbnails/assets/icon-128x128.png?rev=1753390)
 * [Regenerate Thumbnails](https://wordpress.org/plugins/regenerate-thumbnails/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/regenerate-thumbnails/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/regenerate-thumbnails/)
 * [Active Topics](https://wordpress.org/support/plugin/regenerate-thumbnails/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/regenerate-thumbnails/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/regenerate-thumbnails/reviews/)

## Tags

 * [cpu](https://wordpress.org/support/topic-tag/cpu/)
 * [tim thumb](https://wordpress.org/support/topic-tag/tim-thumb/)

 * 5 replies
 * 3 participants
 * Last reply from: [viper007bond](https://wordpress.org/support/users/viper007bond/)
 * Last activity: [15 years, 6 months ago](https://wordpress.org/support/topic/plugin-regenerate-thumbnails-cpu-usage/#post-1630014)
 * Status: not resolved