Issue report: Excess CPU usage with LrC on macOS Mojave

johnrellis, I happened on the hidden triangle on the identity plate – but not till after I realized that the performance was face recognition going on in the background. But it was good of you to attach the screenshot for those who might not have discovered it.

This indeed is poor design. It's a paradox that an action I initiate (like exporting a dozen photos from my catalog) is readily detected from a progress bar, but a background action like the very CPU-intensive face recognition process is completely concealed unless one knows where to find the secret encoder ring!

I've now played with the face recognition feature a bit. I was pleasantly surprised to find that LR had already made a fair bit of facial recognition progress all the times it was chewing CPU over the past few months. If I hadn't posed the question when I did, the odd pegged CPU behavior might have gone away on its own, leaving me even more confused!

davidg36166309, very interesting that you mention Face Detection. I checked "Catalog Settings... > Metadata > Face Detection" and found "Automatically Detect Faces In All Photos" checked!  I can't imagine having checked that setting, because most of my images are of non-human subjects. However, it's entirely possible that Adobe was unkind enough to set it for me in one of my past upgrades.

Unchecking it brings the performance back to normal levels. Thank you for that suggestion; this caught me by surprise because facial recognition not a feature that I knowingly enabled.

I see from https://helpx.adobe.com/lightroom-classic/help/face-recognition.html that there is more to facial recognition than meets the eye, and I'll have to read this in more depth if I ever want to explore this feature. 

What really surprises me is that there is no indication (other than the solid spike in CPU time) that there is a background task running, unlike during an Export workflow – that would have made the cause more obvious!

Thanks for solving the mystery.

dj_paige, I thought that my statement about this taking place at launch said what was needed, but I can see a potential for ambiguity there. I've updated my post accordingly, coloring the revised text in blue. I'll elaborate further below.

The CPU overloading begins the instant I launch LrC, and takes place without me doing anything with my keyboard or mouse. 

I know from experience that some of the tools in the Develop module (the clone/heal brush in particular) cause CPU load when opening an image. As stated, these are not at play here. Further, the excessive CPU usage takes place regardless of what module Lightroom is in – the bad behavior is the same whether it's in Library, Develop, Map, etc.

Lightroom's misbehavior goes away instantly after the catalog optimization is complete, but returns the next time LrC is launched before I do anything with my images. Hope this helps.