On Fri, Mar 28, 2014 at 10:12 AM, Prateek Saxena <psaxena@wikimedia.org> wrote:

I have never experienced this issue myself. Is there a list of images

that haven't been converted to thumbnails yet. I could create test
pages that link to it and measure performance on developer tools.

You can load the file description page with an action=purge URL parameter, that will delete all thumbnails of that image and they will have to be re-rendered the next time you look at them.

(Or you can just change 300px to 299px which is probably not used anywhere so all images will have to be rendered when you first open them.)