Frequent hangs after importing a large library from Endnote

I recently imported a large Endnote library (using .RIS). Now, my library has about 6,000 items (15,000 with child items). I am encountering frequent hangs of Zotero Standalone that last 5-10 minutes. If I try to interact with the program during a hang, I receive a message "XULRunner is not responding".

I had previously thought this was due to an issue with syncing (Dan Stillman was helping with that), but this behavior persists even after disabling file syncing via WebDAV and auto-syncing the database with zotero servers. I have tried to disable full-text indexing and to check the database integrity, but the program hangs indefinitely whenever I try to do so.

Any thoughts?
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