Cropping to an edge confuses Adobe Bridge?

Question

I use Abobe Bridge as the host application for Camera Raw. For me, it makes much more sense than hunting for images from Photoshop.
I think it's been at least three years—probably longer—since I noticed that Bridge has a habit of extracting some previews when they should already be cached, every time I bring Bridge to the foreground. I tried to ignore it, but as the number of images in the Content panel increases, so it seems that the number of repeat extractions increased. If you are dealing with hundreds of images at once, this can place a heavy load on the computer. An older computer can really struggle. Even with my super duper new computer, the 8 virtual CPUs can shoot up to 50% usage for 10 seconds every time Bridge gets focus because of this issue. And, since Camera Raw 7.3, the situation has got worse.
Adobe Bridge uses Camera Raw to extract Raw previews. And today I made a major discovery (major for me anyway):
Removing cropped images from the Bridge Content panel stops repeat extractions.
One of my folders contained a lot of cropped images—some straightened, some transformed—and every time I brought Bridge to the foreground the computer fan would wind up as 40 or so repeat extractions would appear to occur. As an experiment, I opened all of the cropped images in Camera Raw 7.2 and adjusted them so that there was space around the crop, and they didn't rest against the edge of the original image anywhere. The repeat extractions stopped completely.
I don't know why Bridge is having a problem with cropped images, but it is on my computer. Maybe it is something to do with the XMP data of cropped images. Has something changed between 7.2 and 7.3 in this respect?

Answer 1

Yammer,
Thanks for such a comprehensive reply.
Sorry for the delay in responding but I have been playing around with your settings and it has taken awhile to get to grips with the anomalous consequences I've noticed.
Preliminaries: My test folder comprises a copy of 13 .CR2 images from which all previous Develop Settings were removed followed by removal of the.XMP sidecars and finally a Purge Cache for the folder. In the Bridge Preferences\Cache - 'Keep 100% Previews In Cache' is Unselected and 'Automatically Export Cache To Folders When Possible' is Selected.
Step 1: duplicate your "altered defaults" (3rd last paragraph in your post #17) for all 13 images.
Caused no problems when switching focus away from Bridge entirely or between folders in Bridge. However, closing and reopening Bridge from the test folder initiated new thumbnail extractions (together with 1 cache export - expected). The weird thing is that, AFAICT, there were only 7 extractions. It happens pretty fast with only 13 images but I did it a number of times and am confident that the number did not exceed 8. And here's something quite unexpected: the same problem occurs, with the same number of extractions, when closing and reopening Photoshop (Ps) whilst Bridge has its focus on the test folder.
Step 2: remove automatic lens corrections (for the benefit of others, not you Yammer: Unselect Lens Corrections\Profile\Enable Lens Profile Corrections). I chose this as my initial variation of your defaults because it is not normally one of mine.
This stops the repeating extractions when switching focus away from or within Bridge (which was never there anyway) but also after closing and reopening Bridge and or Ps.
Step 3: add back automatic lens corrections.
Again, no problem when switching focus within or away from Bridge, but the repeated extractions, with the same number, return after closing and reopening Bridge and or Ps (whilst the focus in Bridge is on the test folder).
So, at least for me, contrary to what I believed in my post #10, the re-extractions problem is not resolved, and it seems likely to be related to, if not caused entirely by, whether or not you have selected lens corrections.
Don't know whether any of this helps you, Yammer, but maybe a starting point for further investigation?