An experiment with an 8 bit file tells the tale... Set it one way, save a file, set it the other way, save another file, and see if the file size differs...
The setting doesn't appear to apply to 8 bit files. I think the new menu option is just an easy way to set / clear the registry setting.
No, it does not apply to 8 bit files.
It only disables the ZIP/Flate compression used on 16 and 32 bit/channel images.
The compression time for 8 bit files is negligable.
Thanks for taking the time to run the experiment. Realy appreciate that!
Thanks, Chris. This is very helpful.