The latest core seems to be a lot more efficient.
However, I seem to be having some problems with Windows 10 after the latest upgrade. Sometimes it doesn't find any peers to use, and sometimes it works in burst mode with long gaps between activity. I've more or less decided to revive my old Linux wallet, and move everything into that.
Bring up the Windows Task Manager the next time it seems to be slow. Each time this happens to me, Bitcoin Core is driving the DASD at 100%. I suspect it is LevelDB compacting its database.