Running multiple Photoshops on the same version?

Question

Is there a way to run more than one version of photoshop on the same computer?
You could do it with a virtual machine but I'd like to know if there are other options.
My system has a 6-core CPU (12 threads) and most of my cores are idle all the time.
I work a lot with very heavy files for large format printing that need to be flattened, rasterized, and so on.
Any ideas?

Answer 1

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Behelitho wrote:
I've benchmarked my system with Cinebench CPU test.
I'm sure the test is comparable to my application.
That's kind of a stretch.
I have a decently large PDF file (one of my books).  It is 348MB, 165 pages and contains about 70 full page high resolution images.
I copied the file (to better simulate two different documents), and set Photoshop CS4 x64 and Photoshop Elements 7 (two versions I have installed on a multiprocessor computer otherwise doing very little right now) to open the first set of 10 pages and the second set of 10 pages at 600 ppi respectively.  Each rasterized image came out to about 100 MB.
Photoshop alone rasterized the 10 pages in 6 minutes 35 seconds at a rate of about 40 seconds per page.  It mostly used just 1 thread, as you have described.
With Photoshop and Photoshop Elements working simultaneously on the task, the page rate in Photoshop went down to almost 60 seconds per page (and it finished first). Elements took 90 seconds per page on the first 6 pages (while Photoshop was rasterizing).  It was slower likely because it is a 32 bit app.
Surprisingly, the apps didn't demand too big a memory footprint and didn't even come close to chewing up the entire 8 GB.  I assume they hit the scratch disk reasonably hard, and in my case that would be the same drive for both.  You might be able to do better if you have multiple candidate partitions for use as scratch.
This workstation (a Dell Precision 470 with 8 GB RAM), while older and not nearly as powerful as yours, is good at multitasking as it has two separate Xeon processors, each with one core and Hyperthreading (Task Manager shows 4 threads available).
Tentative Conclusion:  You'll see an incremental throughput gain by running two rasterizations, but not nearly 7 to 1 as your benchmark shows.  Probably more like 1.5 to 1.
-Noel