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Speed Up Saving and Opening Photoshop CS5/CS4/CS3 Files
Related: CPU cores, data compression, hard drive, optimization, Photoshop, RAID, software
Sometimes fast hard drives and ample memory still don’t help—it requires a change in software.
Opening and saving files is about as slow as in Photoshop CS5 as in CS4 and CS3. In spite of the now-prevalent 2/4/8/12 core systems; opening and saving files still runs single-threaded (only one CPU core is used meaningfully). Even if this is due to a file format issue that requires single-threaded operation (unlikely), Adobe could make the save/open operations non-modal so that work could continue on a different image while others are being saved and/or opened.
Uncompressed TIF files occupy more space, but time is frequently more important the file size, and once one is done with a file, it can be resaved as a PSD.
With single-threaded open/save, Photoshop is “CPU-bound”, meaning that its running time is a function of CPU speed. In other words, if 95% of the time is spent computing, disk I/O that takes zero time can only speed things up by 5%.
Example: opening a 754MB test file took 14 seconds on a 4-way striped RAID, and 18 seconds on a single moderately fast hard drive (on my Mac Pro). The modest improvement reflects the CPU-bound single-threaded operation of Photoshop CS5.
Still, 18 vs 14 seconds is a 20% reduction, pointing out the value of a fast striped RAID, something far more cost effective than (for example) a 3.2GHz machine over a 2.8GHz machine, which offers only a 14% speedup. See How to Configure a Mac Pro.
A 5616 X 3744 pixel file consisting of four 16-bit image layers (pixel layers) was used for this test. This file saves as approximately 722MB uncompressed. This is just one example; the times can be expected to vary in similar ratios, but final compressed file size might vary.
Single-layer PSD files save much faster; they are uncompressed which can be verified by creating a large blank file (eg white or gray), then saving it. For example, a 1GB file saves in PSD format as 1.01GB, but compresses with ZIP to 1.4MB! So the issue is really with multi-layer files.
|File Format||Time to save
|File Size zipped later|
|PSD, slow drive (or fast)||48||348.1||n/a|
|TIF: ZIP/ZIP, slow drive (or fast)||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|
Photoshop is using only one CPU core for the save operation. The save can run only as fast as that CPU core, so hard drive speed has little influence. The 4-way striped RAID used here needs about 2 seconds to save a 722MB file. If that time were reduced to zero, then the 48 second save would still be 46 seconds—effectively the same.
If you must save as PSD or compressed TIF, then your only choice is to get faster machine eg 3.2GHz instead of 2.8GHz. That could cut down a 48 second save to about 42 seconds. Not so great for a $1400 premium.
Note that hard drive speed does matter for saving uncompressed TIF files; the time was cut by 56% in this example. Unfortunately, there is no option to tell Photoshop to not compress PSD files, so if PSD format is mandatory, you’re stuck with poor performance.