As described in “Introducing WP Image Processing Queue – On‑the‑Fly Image Processing Done Right“, Image Processing Queue plugin tries to solve several issues with On-The-Fly Image Processing (OTFIP) in WordPress. Some of the things that it improves are:
- Response times for pages with non-yet generated thumbnails.
- Server CPU spikes for pages which use a lot of images on sites with a lot of configured thumbnail sizes (49? really? WOW! I don’t think I’ve seen more than 10 in the wild, which is still a lot).
- Server disk space issues caused by removed images and leftover thumbnails.
This is a very useful direction and I hope all the necessary bits will make it into the WordPress core. But even for those who don’t use WordPress, the whole discussion and implementation are a handy reference.