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Photoshop CS6 Performance — diglloydHuge
The diglloydHuge benchmark requires that Photoshop have available about 56 GB of real memory for itself, which means that a machine with less than about 64GB of system memory will suffer in performance on this test due to the need for Photoshop to write and read from the scratch disk.
The results show clearly that having adequate memory is critical. With memory prices so low, it makes no sense to skimp on memory for a machine that approaches $2500, when 32GB memory is around $220 (as this was written). Even adding 16GB memory to a stock 8GB system would yield 24GB total, a massive jump over the base 8GB.
vs Mac Pro
The iMac is not competitive here. Its 32GB memory limit is the problem.
An iMac with a hard drive (without Fusion) would fare much worse than shown here; the Fusion setup is an all-SSD test here (hard drive not involved).
vs MacBook Pro Retina
The MacBook Pro Retina suffers from too little memory (16GB). Even so, the iMac with 16GB easily outpaces it.
Fusion capacity usage
The Fusion drive performs well if and only if there is somewhat less than 120GB of capacity used. Once 120GB or more is used, the Fusion drive maintains ~4GB of free SSD space, and this drops its performance drastically.
Discussion continues below.
More on Fusion
Curiosity was aroused when the Fusion drive performed so well here. With only 37GB on the Fusion drive (“Fusion 1TB < 120GB”), this meant that the test using Fusion was really only using the SSD only (no hard drive involved).
But what about real world usage? When a more realistic amount of data is stored on the Fusion volume (at least 120GB given that the Fusion SSD is 120GB), what would the performance be, given that the Fusion technology maintains 4GB of free SSD space, not the ~83GB free in the test above.
As expected, creating another 120GB on the Fusion drive “hit the wall” with performance dropping from ~350 MB/sec down to ~150MB/sec while the files were being written to disk.
After creating the file, the system was allowed to idle until the disk I/O activity went to zero, indicating that Fusion had reclaimed its 4GB of SSD working space. In the real world, having 4GB SSD space available might not be the case (consider saving a multi-gigabyte file, then continuing to work with operations that are hitting the disk). Ditto for any kind of program driven batch processing where no pauses are available.
*OpenGL (GPU) was disabled in Photoshop CS6 13.0.3, because it slows things down by a few percent (a result seen repeatedly with many Macs). OpenGL can be helpful for more obscure Photoshop operations, but these are not tested here.
Fusion vs Accelsior PCIe SSD
The Apple Fusion drive had only 37GB used meaning that the Fusion figures are for a Fusion drive which does not use the hard drive portion at all. This is not realistic for real-world use.
The OWC Mercury Accelsior in a Mercury Helios enclosure shows a surprisingly small improvement over the Fusion option in spite of its ~70% faster raw performance. This might be more of a Photoshop limitation than anything else.