On my WP site (which sells retail products), I have large images (up to 4000x4000 px) so people can zoom in. Unfortunately, when adding images to a page and using the Media Library, the images all load up at full quality (though resized down). This makes the Media Library page load up really slowly, and make my browser slow to a crawl. Why is it doing this? Why isn't the ML page using thumbnails? If I click on "Media" on the left admin menu, that list of images are proper thumbnails, but when adding media to a page, the list that comes up is using full quality images.

Is this a bug in WP?

4 Answers 4


If you server does not have the right image libraries installed WordPress can't create actual thumbnails, but can only resize them in CSS. I suspect that that is the problem.

Create a file on your server and put <?php phpinfo(); ?> in it. Then load that file. You will get a table of server configuration information. Look for the presence of PHP's image libraries. I am pretty sure WordPress uses Imagemagick if available, then GD, then nothing. I may be wrong about that though. I am not terribly familiar with the media subsystems.

You can also check the wp-content/uploads folder to see if images are being created in multiple sizes.

It is also possible that a plugin or theme has disabled the image generation.


I had this same problem. I couldn't work out why some images I uploaded early in my development process where showing thumbnails and others uploaded later were showing the full image constrained to 120px wide.

Finally realised it was because I disabled the Medium image size by setting both width and height to 0. It obviously uses the Medium image if available, and if not defaults to the full size. I just set Medium to 120x120 and regenerated the thumbnails (http://wordpress.org/plugins/regenerate-thumbnails/‎) and now all good.


Even though there is an accepted answer, here's some more information for others afflicted by the same issue.

The media modal popup requires there to be a "medium" image size, and for that to be in the "image_size_names_choose" array (that's the filter, anyway). If "medium" is not one of the keys in that array, the modal popup uses the full image size.

Reference: http://core.trac.wordpress.org/ticket/25452


Found the issue. It's with the theme itself, not WP. An update to the theme has fixed it.

  • 2
    Which theme? This question/answer does not strike me as very useful to the general public without that information.
    – s_ha_dum
    Commented Oct 6, 2013 at 17:19
  • Irrelevant now, as the theme owner has fixed the problem. Commented Oct 7, 2013 at 16:25

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