This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.
It's not a bug - it's a mechanism. The plugin doesn't generate the thumbnails directly. The script sends a request for the thumbnail to the central ThumbSniper server. If the URL is requested for the first time, the thumbnail has to be created first. After this is finished, it's cached on the ThumbSniper server and will be delivered much faster next time.
The shown tooltips contain a HTML "img" tag. The source URL of this tag points to the ThumbSniper service. The chosen image size and the URL of the current hyperlink are sent as parameters. The ThumbSniper service stores this data in a database. Then a thumbnail generator gets the order to generate a thumbnail for the stored URL. After successfully generating the image, the ThumbSniper service gets the image. The process of generating the image should take about 3 to 10 seconds. After this, the ThumbSniper service redirects to the correct thumbnail url and - here it is!
The ThumbSniper service is free of cost for you (not for me :-( ).
It is written, operated and maintained by me, Thomas Schulte.