So... the solution is to load all 45,000 books onto your reader and wait 17 minutes whle it tries to perform a global search on 256 MB of RAM?
I guess I cannot really speak to the issue -- I can remember the subject-title correlations of all the thousands of books I have read,
AFAIR.
That is a solution looking for a problem, and the better solution is to just use google.

Vague keyword searches work a lot better there.