How fast are the "Late 2014/Mid-2015" iMac models compared to one another and the "Late 2013" models? How fast are the "Late 2014/Mid-2015" iMac models compared to the Mac Pro?

Please note that the "Late 2014" and "Mid-2015" 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 "Late 2014" Retina 5K iMac models -- the iMac "Core i5" 3.5 27-Inch and "Core i7" 4.0 27-Inch -- Apple mentions "performance" twice, but in reference to "high-performance graphics" and the beautiful display itself, rather than overall performance, per se. The subsequent press release for the "Mid-2015" Retina 5K iMac -- the iMac "Core i5" 3.3 27-Inch -- doesn't mention performance at all in reference to the iMac and instead emphasizes that a lower price tag is its most attractive feature.

Likewise, with even a quick review of a comparison of the "Late 2014/Mid-2015" Retina 5K models and the earlier "Late 2013" iMac line, it is clear that the displays are the most important difference. As all of these lines use the "Haswell" architecture and have similar processor clockspeeds, it would be reasonable to expect the overall performance difference to be inline with the clockspeed differences, too.

As the "Late 2013" Mac Pro models use a different architecture, evaluating the performance difference between these models and the "Late 2014" and "Mid-2015" iMac models definitely will require benchmarks and real world testing alike.

Photo Credit: Apple, Inc. (27-Inch iMac Retina 5K)

General Performance Overview

For a solid overview of the performance difference between the "Late 2014/Mid-2015" Retina 5K iMac line and earlier and later iMac models, 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, the Geekbench 3.0 benchmark shows that the custom configured "Late 2014" iMac -- the iMac "Core i7" 4.0 27-Inch -- is at least 14% faster than the standard iMac "Core i5" 3.5 27-Inch model. As the custom processor option only costs 10% more, it represents a good value.

Compared to the 27-Inch "Late 2013" iMac models, the "Late 2014" Retina 5K models are between a negligible 1% faster and and a more significant 13% faster:

Late 2013 iMac	Late 2014 iMac	Single Core	Multicore
"i5" 3.2 27" "i5" 3.4 27"	"i5" 3.5 27"	10% Faster 3% Faster	7% Faster 1% Faster
"i7" 3.5 27"	"i7" 4.0 27"	13% Faster	13% Faster

Compared to the slowest "Late 2014" iMac -- the iMac "Core i5" 3.5 27-Inch -- the "Mid-2015" iMac -- the iMac "Core i5" 3.3 27-Inch -- is around 6% slower in single core and multicore tasks alike. As it costs 13% less, though, it is not a bad value for somone who places more importance on price than performance. However, keep in mind that the "Mid-2015" iMac has a hard drive rather than a faster "Fusion Drive" and it will be significantly slower in disk-related tasks as a result.

Compared to the two standard "Late 2013" Mac Pro models, the "Late 2014" Retina 5K iMac models are between 8% and 23% faster in single core tasks, but between 17% and 20% slower in multicore tasks:

Late 2013 Mac Pro	Late 2014 iMac	Single Core	Multicore
"4 Core" 3.7	"i5" 3.5 27"	8% Faster	17% Slower
"6 Core" 3.5	"i7" 4.0 27"	23% Faster	20% Slower

Likewise, the "Mid-2015" iMac -- the iMac "Core i5" 3.3 27-Inch -- is about 3% faster in single core tasks than the entry-level "Late 2013" Mac Pro -- the Mac Pro "Quad Core" 3.7 -- but around 18% slower in multicore tasks.

This performance split between the iMac and the Mac Pro in single core and multicore tasks makes real-world application tests particularly useful.

Other Benchmarks & Real-World Test Results

Geekbench provides a convenient overview of overall performance, but other benchmarks and application tests can be particularly useful. Depending on your intended purpose, it may make more sense to get an iMac or a Mac Pro.

As part of a quick review, Macworld compared the "Late 2014" Retina 5K iMac to the Six Core Mac Pro and an older iMac "Core i5" 3.2 27-Inch (Late 2012). In Cinebench tests, Macworld reported results similar to those provided by Geekbench 3.0:

The Mac Pro scored an average [multicore] CPU score of 930, the Retina iMac scored 530, and the older iMac, 452. . . In the single core test, however, the Retina iMac bested the Mac Pro. The Retina iMac scored 142, the Mac Pro 133, and the older 27-inch iMac, 125.

For the "Mid-2015" Retina 5K iMac, Macworld confirmed the Geekbench results that EveryMac.com provides above, but also adds that it was "4 percent slower in the Cinebench R15 CPU test" than the entry-level "Late 2014" iMac.

MacPerformanceGuide compared the "Late 2014" iMac to the Mac Pro running Photoshop tests and was impressed in many respects:

The iMac 5k when maxed-out turns in very respectable performance about 15% slower than the best possible Mac Pro ["Twelve Core" 2.7] until and unless memory runs short.

Although Photoshop performance is solid, on high-end tasks, Jason Snell's Six Colors reported some buggy performance that may be software related:

In my use of the stock system, graphics performance was generally fine, though if I opened a whole lot of windows and spaces and then invoked Mission Control, I could definitely see pauses and stuttering. I have no idea how much of that is the fault of the system hardware, and how much is the fault of the software.

I also found that most of the programs I use worked flawlessly on the iMac, but a few -- most notably Apple's own Logic Pro X -- stuttered badly when I tried to scroll through a timeline or zoom in on a project section. I worked around Logic's performance issues through a little-known technique: You can select an App and choose File: Get Info in the Finder, and you'll see an option to "Open in Low Resolution." With this box checked, Logic worked just fine on the iMac -- albeit without pretty high-resolution graphics.

For gaming, Ars Technica evaluated the "Late 2014" Retina 5K and "issued its judgement" accordingly:

Games at 2560x1440 (or "1440p," if you prefer) look and run great, even with AA and AF enabled. The fact that the GPU is scaling the image up to fit to the underlying 5K pixel grid really doesn't appear, at least to my eye, to yield any of the blurriness that you get when using non-native resolutions on lower-DPI LCDs.

Although this overall judgement is a favorable one, it also is worth noting that attempting to run games at native resolution -- 5120x2880 -- typically cuts frame rates by around 50%, which could make game play unpleasant at best. Of course, native resolution is very high on this iMac, naturally.

Finally, BareFeats also hit the "Late 2014" Retina 5K iMac with an deluge of tests -- covering formal benchmarks, graphics apps, gaming, graphics processors, storage, and more -- and these test results are well worth reviewing, too.

Performance Summary

Ultimately, the "Late 2014/Mid-2015" Retina 5K iMac models provide a beautiful display and solid performance -- even besting the more expensive Mac Pro models available at the same time in some tasks -- and are a good value for the majority of users as a result. However, for those with high-end needs that benefit from multicore performance (like 4K video editing), who like the versatility that an easier to upgrade computer provides, and have an ample budget, the Mac Pro is a better choice.

New & Used iMac Purchase Options

There are many places to purchase a used "Late 2014" or "Mid-2015" iMac. However, purchasing from a quality business with years of experience in the Mac market -- and after sales support -- is the best option and will save you money and time, too.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing sells used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.

In Australia, site sponsor Mac City likewise has a variety of used iMac models sold at low prices and available with a free warranty and fast shipping across Australia.

Please also see EveryMac.com's Ultimate Mac Comparison feature to dynamically compare any iMac model to any other Mac.