I don’t have any of the terms list active except for journal. The oly other thing seems to be the “depth” of your library in the folder structure? This could lead to very long names for your attachments. Also – how many output styles do you have?
If you haven’t already, though, I would consider cleaning up your journal terms list according to the suggestions here: http://endnote.com/kb/82228 and turning off journal auto-updating.
Library Name: Leanne-X7-2015.enl
Location: L:\Endnote libraries RW\Leanne-X7-2015.enl
Last Saved: Wednesday, June 28, 2017 9:38:32 AM
Records: 5654
Custom and Smart Groups: 29
Reference Types Used: 19
Most used ref. types: Journal Article, Book, Book Section, Web Page, Electronic Book
File Attachments: 1229
Figures: 0
Authors Term List: 0
Journals Term List: 17276
Keywords Term List: 1