Not OP and this is mere anecdata, but on a modest several-years-old ThinkPad, Zotero was slow when my single collection started pushing over 1,000 papers, most of which had PDFs attached. Starting up would take many seconds (half a minute?) and heavy operations such as bulk-renaming would take minutes. But for day-to-day use (adding references to my collection via a browser plugin) it was fine.

Personally, I used auto-export for all additional functionality. So, I didn't use any Word (LibreOffice) plugins that hooked into Zotero or whatever. I'd just consume a giant .bib file as and when necessary.

On modern hardware Zotero is probably fine. And it's reasonably flexible. A suggestion: export/import a big refs file (plus PDF attachments) and see if it can handle your daily workload. I suspect it will.