Hi, thank you for reaching out and for taking the time to report this issue with such detailed information.

This scenario will be investigated further to see what might be causing the excessive memory usage and whether improvements can be made.

In the meantime, you may consider temporarily downgrading to PhotoShow 4.89.2 (https://addons.mozilla.org/en-US/firefox/addon/photoshow/versions/). It has more limited support for subframes and does not include some of the latest features, but it should also have lower memory usage.

Further updates on the investigation will be posted here. Thanks again for the report, and cheers!