How fast are the "Mid-2017" iMac models compared to one another? How fast are they compared to the "Late 2015" models replaced and the Mac Pro?

Please note that the "Mid-2017" iMac models have been discontinued. However, this Q&A still can be quite helpful to anyone buying or selling one of these systems on the used market.

In the corporate press release for the "Mid-2017" iMac, Apple focuses on disk speed, stating that the "SSD storage options are now up to 50 percent faster" than their predecessors.

In other promo copy, Apple claims that graphics performance is substantially improved with between 1.4x and 3.0x better performance than the models replaced in video editing, gaming, and 3D graphics-related tasks.

Photo Credit: Apple, Inc. (Mid-2017 iMac Models)

The "Mid-2017" iMac series packs a more advanced processor and architecture as well as graphics processors, so it would be a reasonable assumption that the performance gains compared to their predecessors would be significant. Just how significant requires benchmarks and real-world testing, though.

General Performance Overview

For a general overview of overall performance between the "Mid-2017" iMac models and earlier Mac desktops and notebooks alike, 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.

For example, for the "Mid-2017" iMac models compared to one another, the Geekbench 4.0 benchmark shows that the cheapest 21.5-Inch iMac 4K model -- the iMac "Core i5" 3.0 21.5-Inch (4K, Mid-2017) -- is effectively the same speed single core tasks but an impressive 39% faster in multicore tasks than the entry-level iMac "Core i5" 2.3 21.5-Inch (Mid-2017).

In turn, the entry-level 27-Inch 5K model -- the iMac "Core i5" 3.4 27-Inch (5K, Mid-2017) is 5% faster in single core tasks and 6% faster in multicore tasks than the iMac "Core i5" 3.0 21.5-Inch (4K, Mid-2017).

For those interested in maximum performance from the "Mid-2017" iMac series, Geekbench 4.0 shows that the custom configured iMac "Core i7" 4.2 27-Inch (5K, Mid-2017), which is a US$200 processor upgrade for the standard high-end iMac "Core i5" 3.8 27-Inch (5K, Mid-2017), is 9% faster in single core tasks and 26% faster in multicore tasks. Because it costs 9% more, but increases performance by the same amount in single core tasks and much more in multicore tasks, this custom processor upgrade represents a particularly good value.

"Late 2015" iMac vs. "Mid-2017" iMac Performance

The Geekbench 4.0 benchmark mostly shows that the "Mid-2017" iMac models are faster across the board compared to the "Late 2015" models replaced. Because eight models have replaced seven, EveryMac.com has opted to compare standard models to one another and BTO/CTO configurations to one another:

Late 2015 iMac	Mid-2017 iMac	Percent Faster
"Core i5" 1.6 21.5" "Core i5" 2.8 21.5"	"Core i5" 2.3 21.5"	41%-62% -21%-12%*
"Core i5" 3.1 21.5" 4K	"Core i5" 3.0 21.5" 4K "Core i5" 3.4 21.5" 4K	5%-7% 10%-11%
"Core i7" 3.3 21.5" 4K	"Core i7" 3.6 21.5" 4K	17%-20%
"Core i5" 3.2 27" 5K	"Core i5" 3.4 27" 5K	8%-14%
"Core i5" 3.3 27" 5K	"Core i5" 3.5 27" 5K "Core i5" 3.8 27" 5K	8%-12% 10%-15%
"Core i7" 4.0 27" 5K	"Core i7" 4.2 27" 5K	6%-10%

*The entry-level iMac "Core i5" 2.3 21.5" (Mid-2017) only has two cores whereas the higher-end iMac non-4K "Late 2015" model -- the iMac "Core i5" 2.8 21.5" (Late 2015) -- has four cores. Consequently, the "Mid-2017" model is 12% faster in single core tasks, because of its faster architecture, but 21% slower in multicore tasks, because it has half the number of cores of its predecessor.

With the potential exception of the change to the entry-level non-4K iMac models between lines, Geekbench 4.0 shows that the performance increase between these models and their predecessors is significant.

"Mid-2017" iMac vs. "Late 2013" Mac Pro Performance

The Geekbench 4.0 benchmark soundly demonstrates the performance difference in single core and multicore tasks between the high-end 27-Inch "Mid-2017" iMac and the much older "Late 2013" Mac Pro models:

Mid-2017 iMac	Late 2013 Mac Pro	Single Core	Multicore
"Core i5" 3.4 27" 5K	"Quad Core" 3.7	+26%	+8%
"Core i5" 3.5 27" 5K	"Six Core" 3.5	+33%	-15%
"Core i5" 3.8 27" 5K	"Eight Core" 3.0	+35%	-32%
"Core i7" 4.2 27" 5K	"Twelve Core" 2.7	+67%	-25%

Geekbench 4.0 benchmarks show that the entry-level "Mid-2017" iMac -- the iMac "Core i5" 3.4 27-Inch (5K, Mid-2017) -- is faster than the Mac Pro "Quad Core" 3.7 (Late 2013) in single core and multicore tasks alike.

However, the remainder of the "Mid-2017" iMac models compared to the much older Mac Pro models are faster in single core tasks, but still notably slower in multicore ones.

Other Benchmarks & Real-World Test Results

Geekbench benchmarks provide a good overview of overall performance, but additional benchmarks and real-world tests also can be useful, particularly given Apple's emphasis on disk-related and graphics tasks.

PCMag reviewed both the 21.5-Inch and 27-Inch models and for graphics performance, specifically, the publication reported:

The [iMac "Core i5" 3.4 21.5-Inch (4K, Mid-2017)] showed respectable scores on our 3D gaming tests. It returned playable frame rates (above 30 fps) on the Heaven (45 fps) and Valley (64 fps) tests at medium-quality settings. When we ran the same tests at ultra quality in its native 4K resolution, the results were much too slow for smooth animation. That said, the 2017 iMac is measurably better at 3D tasks than systems with integrated graphics, like the 2015 iMac 21.5-inch [model]...

The [iMac "Core i5" 3.4 27-Inch (5K, Mid-2017) with its] AMD Radeon Pro 570 with 4 GB of VRAM is an increase over the 2015 model's 2 GB Radeon R9 M290. Animation and rendering software will be faster on this version thanks to the upgrade, which will benefit creative professionals. As for gaming, the 2017 iMac was able to average over 30 frames per second on the Heaven and Valley tests at ultra-quality settings and HD resolution, though the 5K native resolution is, of course, a bridge too far for the hardware.

BareFeats hit the top-of-the-line custom configured "Mid-2017" iMac -- the iMac "Core i7" 4.2 27-Inch (5K, Mid-2017) -- as well as the Mac Pro "Eight Core" 3.0 (Late 2013) and an even older Mac Pro (2010/Westmere) model upgraded with dual "Six Core" 3.33 GHz processors with a number of professional applications like Final Cut Pro X, Premier Pro, After Effects, and more.

The site concluded:

Analyzing your pro application's performance can be frustrating. Some functions are CPU intensive. Some are GPU intensive. Some are a mixture of both. In some cases the 2017 iMac 5K 4-core acquitted itself very well compared to the 12-core Mac Pro tower and 8-core Mac Pro cylinder. At other times, it was left in the dust.

Finally, MacPerformanceGuide compared the "Mid-2017" 5K iMac to the "Late 2015" 5K iMac as well as the "Late 2013" Mac Pro.

Comparing the 2015 and 2017 iMac models with an Apple 1 TB SSD, the site found that the "Mid-2017" iMac provided "outstanding" sustained disk performance using large files -- "40% faster for reads and 38% faster for writes" -- but its performance actually was "substantially slower for everyday tasks that involve intensive I/O with smaller reads" when transfer sizes are less than 1 MB.

For Photoshop, in a series of its own benchmark tests, the site discovered:

The 2017 iMac 5K offers a substantial speed boost over its 2015 predecessor and boots the fastest possible Mac Pro into 2nd place.

However, it also is worth noting that by upgrading the processor in the Mac Pro, it still is possible to create a Mac Pro that is faster than the much newer "Mid-2017" iMac models, even though Photoshop does not take full advantage of multicore processors.

Performance Summary

Ultimately, the "Mid-2017" iMac models provide a significant speed boost compared to their predecessors in overall performance, graphics performance, and disk performance. They trounce the much older Mac Pro models in many single core tasks, too.

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