I am using PHP 5.3. After saving the plugin configuration it immediately ramped up my load average, and froze the blog. Had to delete the plugin via FTP for everything to go back to normal.

I’d rather see a plugin like SpriteMe that allows a sprite snapshot that can be saved in the theme folder. When changes on the blog are made a new sprite snapshot image file can be made. Using a static image would be far better than one generated by the plugin. I don’t see anyone changing their blog design every 10 minutes which is the default for the cache to expire.