I'm using WebDAV from my Synology NAS to a bunch of Android devices. About 3000 notes (9000 files) and on most devices it's taking around 6-7 seconds. Everything from a super-slow Tab A8 to a more recent (but still antique in this field) Tab S7+. The initial sync of each device can take many hours due to the >35000 "resources" involved but after it's done it works perfectly.