How fast are the "Late 2017" iMac Pro models compared to one another? How fast are they compared to the "Mid-2017" 27-Inch iMac 5K models and the "Cylinder" Mac Pro?

In the corporate press release, Apple declared that the "Late 2017" iMac Pro is the "fastest, most powerful Mac ever made."

Photo Credit: Apple, Inc. (27" iMac 5K - Left, iMac Pro - Right)

Official Test Results

Apple's press release continues and compares the iMac Pro to the fastest "Mid-2017" iMac -- the iMac "Core i7" 4.2 27" (5K) -- in quite a bit of detail for PR, declaring that with the iMac Pro:

• 3D designers can visualize huge 3D models and render scenes up to 3.4 times faster.
• Developers can run multiple virtual machines and test environments, and compile code up to 2.4 times faster.
• Scientists and researchers can manipulate massive data sets and complex simulations, visualizing data up to 5 times faster.
• Photographers can work with enormous files and perform image processing up to 4.1 times faster.
• Music producers can bounce (export) massive multi-track projects up to 4.6 times faster and use up to 12.4 times as many real-time plug-ins.
• Video editors can edit up to eight streams of 4K video, or edit 4.5K RED RAW video and 8K ProRes 4444 at full resolution in real time without rendering. The iMac Pro can also export HEVC video 3 times faster.

Although these bullet points all sound impressive, it also is worth noting that in fine print, Apple disclaims these results are comparing the fastest custom-configured iMac Pro -- the iMac Pro "18-Core" 2.3 27" (5K) -- rather than the most common and comparatively more affordable stock iMac Pro "8-Core" 3.2 27" (5K) model.

This custom configured iMac Pro model cost US$7399, a whopping 222% more than the custom-configured "non-Pro" iMac, which cost as little as US$2299.

Of course, for many professions, this extra cost is money well spent (time is money, after all), but it also is worth evaluating the performance of the more affordable stock iMac Pro that costs US$4999, merely 117% or so more than its non-Pro contemporary. It also is valuable to compare the other models in the lines as well as the "Cylinder" Mac Pro for a more well-rounded opinion.

Benchmark Results

For a solid overview of the performance difference between the "Late 2017" iMac Pro as well as the "Mid-2017" iMac and the "Cylinder" Mac Pro, EveryMac.com's own Ultimate Mac Comparison makes it quick to compare side-by-side 32-bit and 64-bit Geekbench benchmark averages with all other G3 and later Macs for thousands of possible performance comparisons.

The Geekbench 4 benchmark generally does an excellent job demonstrating the relative performance difference between single core and multicore tasks, in particular.

Late 2017 iMac Pro Models Compared to Each Other

This chart shows approximately how much slower or faster each system is compared to the model immediately before it:

Late 2017 iMac Pro	Single Core	Multicore
"8-Core" 3.2	Baseline	Baseline
"10-Core" 3.0	4.5% Faster*	15% Faster
"14-Core" 2.5	0.85% Slower	15% Faster
"18-Core" 2.3	0.40% Slower	18% Faster

*Interestingly, you would expect the 8-Core model to perform fastest in single core tasks because it has the fastest clockspeed, but it does not running Geekbench 4. Whether this reflects a flaw in the benchmark or a performance limitation of the particular processor in the entry-level model, perhaps due to downclocking, remains to be seen, but this Q&A can be updated if the data changes over time as additional benchmark results are averaged.

In a direct comparison between the entry-level model and the highest-end custom configured model, the entry-level iMac Pro "8-Core" 3.2 27" (5K) is roughly the same speed as the high-end iMac Pro "18-Core" 2.3 27" (5K) on single core tasks. On multicore tasks, though, the high-end model is a whopping 57% faster than the entry-level one.

Mid-2017 iMac & Late 2017 iMac Pro Compared to Each Other

This chart shows approximately how much faster or slower the "Late 2017" iMac Pro model is compared to the non-Pro iMac:

Mid-2017 iMac	iMac Pro	Single Core	Multicore
"Core i5" 3.4	"8-Core" 3.2	6% Faster	121% Faster
"Core i5" 3.5	"10-Core" 3.0	3.7% Faster	140% Faster
"Core i5" 3.8	"14-Core" 2.5	1% Faster	170% Faster
"Core i7" 4.2	"18-Core" 2.3	7% Slower	153% Faster

The above comparison between the two high-end options (last row) -- the same non-Pro iMac and iMac Pro that Apple uses in its press release -- show that the iMac Pro is indeed a gigantic 153% faster in multicore tasks, but actually 7% slower in single core tasks. "Slower in some tasks" would not be nearly as good of a marketing slogan as "fastest Mac ever" though.

In a direct comparison between the high-end iMac -- the iMac "Core i7" 4.2 27" (5K) -- and the entry-level iMac Pro -- the iMac Pro "8-Core" 3.2 27" (5K) -- the non-Pro iMac is a significant 11% faster in single core tasks but a massive 61% slower in multicore ones.

Cylinder Mac Pro & Late 2017 iMac Pro Compared to Each Other

This chart shows roughly how much faster the "Late 2017" iMac Pro model is compared to Apple's aging professional "Cylinder" Mac Pro:

Mac Pro	iMac Pro	Single Core	Multicore
"Quad Core" 3.7	"8-Core" 3.2	34% Faster	138% Faster
"Six Core" 3.5	"10-Core" 3.0	38% Faster	103% Faster
"Eight Core" 3.0	"14-Core" 2.5	37% Faster	85% Faster
"Twelve Core" 2.7	"18-Core" 2.3	55% Faster	91% Faster

Unsurprisingly, given that Apple has not updated its professional desktops in years, the "Late 2017" iMac Pro crushes the "Late 2013" Mac Pro across the board.

Real-World Test Results

Geekbench 4 provides a helpful overview of overall performance, but real-world test results also can be useful for more perspective with specific applications.

In Final Cut Pro and Adobe Premier export tests, 9to5Mac reported results from videographer Dom Esposito that were similar to Apple's official numbers for multicore software:

The iMac Pro export only took 1 minute 24 seconds which beat the iMac's export time of 4 minutes 5 seconds by a whole 2 minutes and 40 seconds. You can imagine that difference being in more dramatic with longer 4K footage and saving a few minutes per export adds up, but Dom concludes that it may take a while for that to make the extra $3200 really worth it.

Similarly, he tested exporting a 2 minute 18 second long 4K project from Adobe Premier where the difference was even more dramatic. The iMac Pro completed the export in 3 minutes 47 seconds while the iMac took a full 9 minutes -- a full 5 minutes 13 seconds difference.

In scientific application testing, Craig Hunter compared the 10-Core and 18-Core iMac Pro models and concluded:

We see performance increases ranging from 27% to 79% for the 18-core iMac Pro when compared to the 10-core model. I suspect many computations and applications will be in the middle of that range depending on how well they can take advantage of multiple cores, but there will certainly be some hot rod uses that get closer to that 79% end of the scale (and may do even better). Though I haven't mentioned it, if you look back through the various benchmark results, you'll see that the 18-core iMac Pro shows no disadvantage for single-core performance, despite running at a lower clock speed (2.3GHz/4.3GHz) than the 10-core iMac Pro (3.0GHz/4.5GHz). Often times, the price of scaling a CPU architecture to more cores is a loss of single-core performance, but no such penalty seems to exist here. The 18-core iMac Pro brings 8 more cores to the table on the high end with no loss of performance on the low end.

MacPerformanceGuide was disappointed with the iMac Pro running Photoshop and reverted to using a non-pro iMac. For a scripted task that creates "a range of output JPEGs of varying resolutions for each layer" for example, the professional photographer lamented:

I would love to get more speed out of the iMac Pro here for this frequent workflow task, but the 2017 iMac 5K rocks it. On the other hand focus stacking is substantially improved with the iMac Pro, and I do that a lot also. Still, it is disappointing that no iMac Pro configuration can beat the 2017 iMac 5K.

The huge variation between these results definitely shows just how critical software optimization can be for multicore systems.

Performance Summary

Ultimately, the "Late 2017" iMac Pro models are extremely fast in multicore tasks and running well-optimized software, Apple's marketing hyperbole of being the "fastest, most powerful Mac ever" is reasonable.

However, running software that only is optimized for a single processor core, the custom configuration of the "Mid-2017" iMac -- the iMac "Core i7" 4.2 27" (5K) -- actually is commonly faster and much, much cheaper. Accordingly, this "non-Pro" iMac represents a particularly good value for many users.

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