With Photoshop CS4, I hoped that Adobe would provide some real, everyday value for the steep upgrade price. After all, an upgrade should improve usability, which means making common, everyday tasks faster and easier. Unfortunately, opening and saving files is still just as slow as in CS4 as in CS3. It’s clear that no attention was paid to this crucial area, in spite of the now-prevalent 2/4/8 core systems. Just making the save/open operation non-modal (so you could on another image) would be a big step forward, even if it remained brain-dead single-threaded.
I measured saving a 5616 X 3744 pixel file consisting of four 16-bit image layers (pixel layers). This file saves as 722.1MB uncompressed. Photoshop CS4 remains single-threaded for saving and opening files (see Multi-core Computers). This means that even if you have a Mac pro with 8 cores, only one of them gets used! It also means that a fast disk is almost irrelevant for save and open operations
|File Format||Time to save
|File Size ZIP|
|PSD, slow drive||48||348.1||n/a|
|TIF: ZIP/ZIP, slow drive||59||450.6||n/a|
|TIF/uncompressed, slow drive||7.4||722.1||525.4|
|TIF/uncompressed, 2-drive stripe||3.5||722.1||525.4|
|TIF/uncompressed, 4-drive stripe||3.2||722.1||525.4|
What’s going on here is that Photoshop CS3/CS4 is using only one CPU core for the save operation. The save can run only as fast as that CPU, so a fast hard drive makes little improvement. My 4-way striped RAID only needs about 2 seconds to save a 722MB file. If that time were zero, then the 48 second save would still be 46 seconds—effectively the same.
The compression and other stuff (whatever it is) in PSD or TIF format is a killer: it takes 7-8 times longer to save a file than without compression. If your work is being held up by this factor, save as uncompressed TIF, and onto a striped RAID. The latter provides a speedup of 13 times!