Quote from Donna Cox Baker on April 14, 2019, 3:54 am

Recently, I noticed that it has started to take a very long time for Zotero to sync and let me start working. Today, I think I found the flag that caused that to start. I chose Edit--Preferences, then the Sync tab. In the bottom section of the screen, in the field "Sync attachment files in My Library using ...." I have it marked "Zotero," which is the default. But mine was set to "Download files at sync time." Now I've changed it to "Download files as needed." It syncs quickly now, as it used to. It will take a few seconds anytime I ask it to get an attachment--but I rarely create attachment links on the Zotero.org side of my syncing. This should be much more efficient.