Dual Core vs. Quad Core MBP speed difference?

[Marbles1]

Is there much of a 'real world' speed difference between each top end macbook pro:

13" non-Retina 2.9GHz dual-core Intel Core i7
15" non-Retina 2.3GHz quad-core Intel Core i7
13" Retina 2.6GHz dual-core Intel Core i5
15" Retina 2.7GHz quad-core Intel Core i7

I'd like to get a new MacBook Pro, but the 15 inch is too big for my needs, it's frustrating that a high end specced model is not available in a 13" form-factor....

Why does the 13" retina model have a slower processor than the non-retina model????

 

[pgiguere1]

You can order a faster 2.9/3.0 GHz CPU as BTO in the 13" rMBP. It's a $200 extra.

The difference will mainly be observed in applications that push the CPU to its full load: video editing renders / encoding, file decompression, some Photoshop effects, gaming...
If you're mainly using a web browser, Office and iTunes, your CPU usage probably will never go over 20-30% either way, so your CPU doesn't really matter. When booting or installing/opening apps the loading time is more dependant on your SSD than anything.

I'd personnally save myself the money for something that makes a bigger difference if your usage is light. I got the 2.6GHz BTO option on my 15" rMBP since it was only a $100 extra (pretty low by Apple's standards) but I regret it now, seeing how low my CPU usage is most of the time. The few times my CPU is at full load, the faster CPU saves me so little time (8%) the $100 investment wasn't really worth it.

If I were to buy a 13" rMBP I think the best deal is the 2.6GHz model without any BTO option, but that's just me.

 

[alphaod]

Day to day use (ie: productivity, web browsing, email, etc.) there is no difference.

A lot of professional apps like Photoshop have many single threaded tasks that would not take advantage of multiple cores.

In a few pro apps the 15" MBP has an Nvidia GPU can take advantage of CUDA.

 

[nontroppo]

But even for single-thread dominated apps, dual vs. quad core means you are much less likely to get hard context locks and hangs when the OS and the app both are doing stuff. My experience is that there is a substantial difference going from single->dual and dual->quad, but that benefit tails off with octocore and dodecacore machines. The larger CPU counts only really come into play when software is multi-thread optimised. But for me a quad-core processor is a substantial improvement of a dual-core for most work that requires multitasking or even singletasking day-to-day stuff when you wat the OS to do something at the same time...