Lightroom 6 / CC2015 - Facial Recognition Terribly Slow, not using all of CPU or GPU, still keeps going when paused.

Question

This is actually a couple of issue but wondering if others are experiencing it and worked through it.
I am using a Dual Xeon CPU 3.2 ghz Mac Pro, Catalog on SSD, Images files on Mirrored Pair, Dedicated GPU (max I can install in my version of Mac Pro) and hardware acceleration enabled in Lightroom.
I watched the Lightroom 6 Facial Recognition tutorial which leaves out a lot of the bulk editing and says basically let it loose on your whole catalog.. NOT recommended.
I started out with a couple small portrait galleries that identified a couple hundred total people to seed facial recognition so it didn't suggest everyone is the first person I confirmed (which it will do otherwise). I have also optimized my catalog multiple times.
I have encountered the following serious performance issues and bugs with Facial Recognition.:
Lightroom Facial Recognition goes to a ridiculous crawl after about 2000 images to be confirmed. (i.e. 2000-2300 in a couple hours, 800-1200 in the next 12 hours)
Lightroom becomes largely unresponsive after having a fair number of images to be confirmed, even after pausing Address and Facial Recognition. So even selecting 4 rows of images can take 5 minutes with several long pauses.
Once I select and click confirm it takes up to 2 minutes to update the "to be confirmed" list again.
When I click on an individual at the top of the page, pause facial recognition and address lookup it still continues to "Look for similar faces" [BUG!!!!!!!!] even though all I want to do is just confirm some individuals more quickly in bulk with the images already identified.. not continue to look for more as a work around for the painfully slow responsiveness of the module.
The odd part is that with all of the performance issues Lightroom will not use more than 20-30% of my two Xeon CPUs, barely touches my GPU (<10% CPU, 30% memory), my and no more than 35% of my memory. Computer Temps are also barely above startup temperatures and 15-25 degrees cooler than when I run other applications which will consume my entire CPU and memory if I let it. I have explored Lightroom's settings but seen nothing further I can configure to speed it all up.  I have also attempted the operation on images on the SSD, my drobo (known to be slow), an independent fast disk I have, and a pair of raided disks and have the same issues.
I will also note that all of my other applications seem to continue to operate just fine.. the slowness seems to be contained to the Lightroom application itself.
Lightroom version: 6.0 [1014445]
Operating system: Mac OS 10 Version: 10.10 [3]
Application architecture: x64
Logical processor count: 8
Processor speed: 3.2 GHz
Built-in memory: 18,432.0 MB
Real memory available to Lightroom: 18,432.0 MB
Real memory used by Lightroom: 5,537.5 MB (30.0%)
Virtual memory used by Lightroom: 32,240.6 MB
Memory cache size: 4,342.0 MB
Maximum thread count used by Camera Raw: 8
Camera Raw SIMD optimization: SSE2
Displays: 1) 2048x1152
Graphics Processor Info:
NVIDIA GeForce GTX 285 OpenGL Engine
Check OpenGL support: Passed
Vendor: NVIDIA Corporation
Version: 3.3 NVIDIA-10.0.31 310.90.10.05b12
Renderer: NVIDIA GeForce GTX 285 OpenGL Engine
LanguageVersion: 3.30
Application folder: /Applications/Adobe Lightroom
Library Path: /Users/DryClean/Documents/Lightroom_Catalog/MyCat_LR6.lrcat
Settings Folder: /Users/DryClean/Library/Application Support/Adobe/Lightroom
Anyone have any suggestions?

Answer 1

A big problem continues to be that once you wait for it to index all your faces you find it missed over half of them. There are many cases where it missed the subject of the photo but managed to find a tiny waiter off in the shadows. I don't know how this will ever get fixed; it seems it'll require an update that lets you rerun the indexing a few times, maybe with different levels of granularity. I doubt that's coming.
It stands to reason that a system that hands you thousands of false positives for every face can't recognize if something is or isn't a face in over half the cases. Faces in profile or tilted down, especially with the eyes looking down, are bypassed completely. I have directories with a thousand people shots in them, many with multiple people, and instead of LR6 returning an index of 1.5k or so, it gives me 385. I'm not sure how valuable the search advantages will be in this case; I can see it not returning some favorite shots of people.
Anyway, for anyone looking to get past the spinning wheels, work on one directory at a time. Then once a directory is done, keep it selected so you have the same thumbnails of identified faces in the confirmed area, and control-select the next directory. You won't have to reseed the confirmed faces area this way and things move much faster when you're not working with the entire library. It also helps to click each person in the confirmed faces and work in that view sometimes. It'll return faces of family members of that person and you can rename those. You can watch it focus its top results as you confirm but, annoyingly, it doesn't narrow the total suggestions but actually expands them the more faces you confirm and the fewer correct positives remain. (This seems opposite to how it should work. It should give you fewer faces the more you confirm as it gets a better idea what the person looks like and has fewer shots left unconfirmed of that person.)  Yet, even with the expanded results, faces will still escape it and pop up in other people's results as false positives.
Bottom line: It's only a little better than manual tagging, and not as thorough because of the poor hit rate of the initial indexing. But it works better if you stick to isolated directories and occasionally individual people. At least that way you don't have to wait for it to re-sort tens of thousands of results with every click.