I have a library (Endnote version 9.0, PC, Windows XP) with approx. 7,700 entries. The last item ID is about 9500. Lately importing other Endnote libraries and deduplicating at the same time has been slow, and today it just gets hung up (program is “not responding” in Windows task manager).
I have tried saving the library as a new library and importing to the new library but the same things happens.
The larger your library, the longer it will take to perform any operation with it – but it certainly shouldn’t freeze up quite as often as you describe. It’s possible that you have some kind of damage or corruption to your library’s index, in which case the best solution would be to run a library recovery procedure as detailed in http://endnote.com/support/faqs/Database/faq3.asp . Does that help?