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I need a new Macbook Pro and am comparing the 13 inch Retina 2.6GHz with the 15 inch Retina 2.0GHz.

I understand that 2.6GHz is faster than 2.0GHz but how does CPU performance compare between the two models with regards to Turbo Boost?

The 13 inch boosts up to 3.1GHz whereas the 15 inch boosts to 3.2Ghz.

My old MacBook didn't have Turbo boost and I use photo and video editing software.

I'd prefer the bigger screen but am mindful of cost.

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    Take a SSD for sure and it's way faster than comparing that CPU. – Rob Feb 10 '14 at 15:02
  • @Robuust All retina MBP have SSD that Apple doesn't upgrade and RAM that is fixed to the logic board. Unless the OP needs to have upgradeable RAM and chooses the 13 inch non-retina with an even slower CPU - an SSD is given at this point. – bmike Feb 10 '14 at 15:08
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It's quite simple from my perspective - The 15 inch CPU is superior in all respects over the 13 inch CPU:

  • 2.0GHz quad-core Intel Core i7 processor (Turbo Boost up to 3.2GHz) with 6MB shared L3 cache
  • 2.6GHz dual-core Intel Core i5 processor (Turbo Boost up to 3.1GHz) with 3MB shared L3 cache

Turbo Boost engages for operations where only one core is active. Starting at a lower GHz saves energy and battery and as long as the CPU can boost to a faster top level than a competing CPU - you get the best of both worlds - fuel efficiency at idle and top speed when needed.

So, for a simple task where the computer is doing one thing only - you would expect the 13 inch to ramp one core up to 3.1 GHz whereas the 15 inch would ramp up to 3.2 GHz. Bigger is better for that task. Plus a larger L3 cache will make some switching between tasks more efficient on the 15 inch model.

Now, if you have video processing or a mixed workload where tons of compute is waiting for the CPU. You have two cores running at 2.66 or 5.32 GHz of theoretical throughput compared to 4 cores at 2.0 or 8.00 GHz of throughput. Again, no task scales perfectly, but even with 10% overhead, the quad core processor wins. It would have to be a bizarre benchmark to show the dual core i5 out perform the quad core i7 for any task that engages multiple cores.

If you want another opinion, I would recommend this nice article by Marco Arment on trying to calculate which Mac Pro CPU choice works for various budgets and tasks:

In it, he doesn't explain why he feels the 15 inch MacBook Pro is so far superior to the 13 inch MacBook Pro and simply states it as fact. I generally agree with that due experience and seeing benchmarks/reviews I trust. My feeling is the current 15 inch logic board and supporting components are faster and of better specifications than what is put into the 13 inch model. If you can swing the cost and live with (or prefer) the larger physical size, get the 15 inch model. It's an excellent workstation in a portable form factor. For many tasks it benchmarks as fast as an iMac and even the new Mac Pro.


Personal note: The base $1299 13 inch model is no slouch - I work from one almost exclusively the last year and I'm never really waiting for it in practice. If you need to pinch pennies on the CPU, I'd con side any of the retina 13 inch models if it means you can afford AppleCare, an external monitor plus backup drive(s) and whatever software you need to be productive. Rather than invest in tons of extra CPU cycles that you may not really use or need to work day in and day out.

  • imore.com/… This article advises that RAM cannot be added later as it is soldered to the motherboard. I was considering upgrading the RAM after purchase to reduce the cost. I will mainly run Aperture, so do I need 16GB in the 15inch Retina for best performance? If so do I have to purchase through Apple because RAM cannot be added later? – APS Feb 10 '14 at 15:00
  • @aps Here's my take - you can sell any newish Mac for almost full price - so buy what you think you need and if you mis-judged, sell and buy in 6 months or when the next model gets released. If you don't really know your workload - get by with the cheapest computer you can and then buy up (perhaps on sale when new models arrive) when you know what you need. RAM enables you to run many things at one time and rarely is the performance bottleneck for a CPU intensive task which is where this thread started :-) – bmike Feb 10 '14 at 15:04
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The MBP 13" has a dual-core CPU, the MBP 15" has a quad-core CPU.

The difference in performance between dual-core and quad-core processors is hard to predict. Quad-core CPUs aren't twice as fast as a dual-core CPUs since not every application takes advantage of multiple cores.

More heavy applications like video editing software or browsers like Google Crome are optimised to use multiple cores.

In overall experience (if not always) the quad core processor will be faster, but it really comes down to what you do with your system to make out if the cost is worth it or not.

  • Btw the Quad Core has a 3.2 Turbo. – Matthieu Riegler Feb 10 '14 at 13:11
  • @JorisVanhecke Thanks for your answer. Can you explain how the Turbo Boost works to increase performance with the different cores? – APS Feb 10 '14 at 13:28
  • @APS I wouldn't pay to much attention to Turbo Boost. It is a feature which activates when only 1 or 2 cores have a load and a single-threaded application takes up many resources. Which rarely ever happens as OSX tries to avoid this. – Joris Vanhecke Feb 10 '14 at 13:57
  • I offered a very different opinion. From what I can tell, the 15 inch CPU is far and away better - whether for single threaded tasks, a mix of tasks (benchmarks or real world tasks like copying thousands of files / opening several apps, rendering video, etc..) or benchmarks designed to stress test multiple CPU cores. What I think is hardest to predict is if you "need" a faster CPU since most computers sit idle most of the time and rarely are run at even 75% CPU workload for times when you are waiting on the computer for a task to finish. – bmike Feb 10 '14 at 14:34

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