Live Picture was one of several photo compositor tools that focused on Photoshop’s pain points. Fauve Matisse was a little earlier than Live Picture and I believe it introduced layers to Mac photo editing. They ended up getting acquired by Macromedia (or perhaps even Macromind) after a rewrite to compete with Live Picture it was renamed Xres and then abandoned.
It was ported over to Irix (and Sun/Solaris/HP-UX and Rhapsody) using a toolkit called Lattitude[1], sort of a reverse-engineered Mac toolbox, that translated Mac API calls to the appropriate Unix/Motif/$Whatever calls, using the native look and feel.
The earlier version was used to port MS Word/Excel to Unix. Metrowerks purchased it for porting (classic) Mac apps to Rhapsody.
I believe that Livepicture was fast because they loaded the full image as a set of tiles.
I also believe that Photoshop was 'inspired' to introduce layers in version 3 in response to Livepicture's layers. It was layers which caused Photoshop to explode in popularity.
Adobe then went on to sue Macromedia for using tabs in their interface. Bummer.
The way to go back then was the SGI Indigo w/96MB.
It worked best for me in the late '90's on a 9500, and even then needed an entire GB of RAM.