Here is an interesting outcome for me. I read that article and one of the throwaway lines in the solution was that permissions were involved. It then immediately shifted to how to change the nice settings using renice. But the permissions comment got me thinking. Photo Agent was using about 30% of CPU for me where before it never made it above a fraction of that. But I had created a new account for me and moved my files from an old account with issues to this new account. I had thought I had shifted it through an external drive to get rid of ownership, but I noted that every once in a while when I opened a document, particularly in Word, it complained that I needed to make a second copy as I only had read access and not read/write access. So, just now, I noted that Photo Agent was about 35%, so I went to /Users/my folder and did a Get Info on it, unlocked the padlock and applied the permissions to all subfolders in my Home directory. Took a while for it to run, but as soon as it was done, Photo Agent disappeared from the first page of Activity Monitor, and it is now showing 0% CPU. Given that Activity Monitor can show tenths of a percent, that means that while it is still there, it's taking less than 0.05% of CPU.
Could that maybe be at play for the OP? Is it worth looking at?
