In my experience, Endnote on MacOS has been slow for the last 3 versions. EN is not slow when interfacing with Word, reference inserts and bibliography updates are as fast as they used to be.
The problem lies with the EN software itself. The following is very reproducible: select any article within any list in your library. Hit the down arrow to move to the next article and continue doing that. After about 10 selections, you start to see a very noticeable delay between the keyboard arrow and the list selection. Opening a reference then takes several seconds. It’s all downhill from there. In the end, it becomes totally unworkable.
This happens with any EN database: large or small, pdfs, no pdfs, Word active, Word not active, it doesn’t matter. You can easily reproduce it even on the tiny example datasets they include with the software.
I suspect this behavior is probably due to a memory leak that Clarivate is unable or unwilling to fix.
When you contact Support, they always try to pin the blame on the user: is your library on a shared drive/network/cloud? (No, it isn’t). Is your database large? (Well, about 4000 records, but it occurs even in small libraries with less than 100 records). Do you have a lot of pdfs in the library? (No, not a single one). At that point, they stop responding and drop your case.
Apart from the fact that EN still looks the same (and does the same) as they version I started to work with in 2008, they always force you through (paying) upgrades whenever MacOS makes a meaningful version upgrade. So you pay and get nothing new in return.
Maddening! So frustrated with this! Unfortunately there are few alternatives out there…