From what i'm reading the cores are split into two clusters, 4 cores are slower Cortex A7 cores and the other more powerful 4 cores are Cortex A15 cores. This allows applications with little hardware demends to run off of slower cores hence power stays down as well as heat output i would imagine.
Cellphones don't need that kind of processing power. It's not like you are going to use a cellphone to run financial and scientific modelling programs, 3D rendering programs, or video encoding. All of which needs some serious amount of CPU power and with the exception of video encoding at least 16GB of RAM.
Since Apple plans to cut ties with Intel in the future, they are developing an ARM processor for their Macs & MacBooks. Some aspects of it may be eventually incorporated in the ARM processors used for iPhone and iPads. But even then cellphone and iPad ARM processors will still be weak in comparison to what's going into desktops and laptops.
ARM processors for tablet and phones pales in comparison to the power of a desktop CPU. In terms of overall performance, ARM is probably has the processing power of a Pentium 3 CPU.
That will likely change when Apple releases an ARM processor for their desktops and laptops because it will need to compete against whatever CPU Intel will have whenever that happens though.
These Mobile processors are far inferior to desktop processors!
The Galaxy S4 Octa Core Processor takes between 8 - 12 Seconds to display a Full Desktop Website. Between 4 - 8 Seconds for a limited Mobile Website.
In comparrison a 400 MHz Pentium 3 / Atom CPU can load a Full Desktop Site in under a few Seconds. A 1 GHz CPU can load a webpage in under a second.
There is no way these Mobile processors can run fully featured Word Processing / Spreadsheet Programs. Where as a 500 MHz - 1 GHz processor can run KDE Linux and Calligra Office.
MeeGo (Mobile Linux) & Calligra Mobile will run on a Atom Processor which is approx 300 MHz.
The Higher end Atom Processors 400 MHz give better performance.
Windows is more optimised and will run Office on a Minimum of 233 MHz and 300 MHz for good performance.
I dont know how Apple is going to release an ARM processor for their desktops and laptops since they are severly underpowered. It is because of this reason they consume little power.
Upping the power will just increase battery drain and x86 Processors are nearly 20 % more efficient ( performance / energy consumption ). Thats why they use Intel processors for their Mac Books. They import Japaneses ARM Cores since their own fabrication will result in huge battery drain. x86 is more efficient. Laymen dont know better!
The The Galaxy S4 Octa Core Processor is probably equivalent to a 486 DX4 100 MHz.
To run a Protected Mode operating system you need approx 300 Mhz and 500 MHz for good performance. Future Real Mode CPUs would be able to run Protected Mode Operating Systems and consume the same power as a 50 MHz Processor. Good Performance using half the Energy.
there is an application called when pack. This is the program these tests the fastest supercomputers. I ran it on my i3-4000M and got about 29 Gigaflops. this is an application run on my galaxy s4 comes up with 770 megaflops. that's the difference of about 39 times.