In several topics here, there are concerns about the way the bookmarks could behave.
For instance here, with a proposal of simplier bookmarks without thumbnail:
I personally find the actual bookmark display pretty sweet, and the picture helps a lot to identify the webpage behind the link, but i am concerned about the storage space (especially for mobile clients). For now, creating a bookmark automatically locally downloads the favicon/thumbnail picture, which leads to really messy picture library.
I would suggest that a bookmark remains a “simple” formated URL link.
To keep a fancy display, the bookmark picture could be temporary get from the internet when the user open the block that contrains the bookmark, instead of being locally downloaded. The picture does not belong to the user anymore, and there is no picture without connection. But we stay close to the actual function and meaning of a bookmark, and avoid useless picture storage.
May it is an alternative to add a global option that allow the user to chose of he wants downloaded local thumbnails… But it adds another option and probably maintenance issues.