High Sierra performance problems - efilogin-helper taking a lot of CPU I have a stock 2015 15" MacBook Pro, i7 / 16GB / 512GB, still runs on High Sierra because I am contemplating to do a full clean install instead of an upgrade. Performance has been deteriorating to a point I can no longer be an active participant in video conferences. I'm trying to find out what is the cause of the slowdown and I'm mainly using Activity Monitor as a guide to what is taking a lot of CPU capacity. I think I figured out that including my Projects folder in iCloud wasn't a good idea as JavaScript applications easily install tens of thousands of files through dependency managers. I'm trying to fix that in another Question.

The only thing that stands out as really odd besides to filesystem and indexation related daemons is efilogin-helper hoovering around 50%-100% all of the time. The only hints I find on Google are about the wallpaper which I've reset to solid blue, so my system doesn't use that anymore.

I would like to not only have a practical solution to efilogin-helper taking a lot of CPU but also maybe understand a bit more about troubleshooting these kind of problems.
So I turned off iCloud and it stopped. It's a pity iCloud can't really handle lots of file changes in a performant way so I don't have a final solution for this yet (semi real-time backups of my working folder).