Huge DL2 file bloat from images of search results

Delicious Library 2 (DL2) appears to store search result images -- massively bloating its database, making it awkward to backup.
When adding a new item via "File->New Item" (searching on its name, for instance) DL2 appears to save the details of every search result -- not just the item added the library. The details saved include the cover images that can consume a lot of disk space.
My wife's DL2 library has just over 1,000 items (mainly books) yet the DL2 (sqlite) file is over 1.5GB in size. There are over 120,000 "CoverImage" and over 40,000 "LazyCoverImageData" entries in the database for only 1,000 items! This is the bulk of the disk space. I assume this must be remembering search results.
A 1.5GB file is awkward to backup. I don't want to backup the whole 1.5GB each day, just because a few more books have been added.
It would be nice if DL2 was more backup-friendly.
I would like a way to trim the unnecessary "cached search results" from the database. An SQL statement might do.