This addon worked great on my test site with ~20,000 image attachments, but when I installed it on a larger site with more and larger attachments, it started to error after about 40,000 attachments.
This is what happened to my server while I slept:
All my sites on that server were down, returning 502 Gateway errors. Restarting php-fpm brought the sites back online.
I cannot say for certain that this addon caused the problem, but it's the only new thing I added yesterday before this happened. I uninstalled this addon. When I reinstall it, server load starts to go up right away.
I hope I can get it working without issue, because I really like this addon. It offers a couple unique features, like the options to strip none, preserve all markers (jpegoptim) and also it works well with AndyB's Convert Image addon.