Microsoft's ARM64 support for Windows 10 coming with 'Redstone wave'

Microsoft's vision of Windows 10 is going even broader with recent job postings confirming various plans including support for Windows 10 desktop on ARM and more tantalizing "Windows 10 Mobile x86" (cough, Surface Phone).

Now, another job description posted confirms plans for Windows 10 ARM64 support coming with the Redstone releases slated for this year. The job is for a Senior Program Manager and was spotted by WalkingCat (aka @h0x0d). With the job posting comes some interesting bits about Microsoft's plans for their all-powerful OS.

The Microsoft Careers job posting notes the following about the 'OS Foundation PM' job:

"Do you want to help usher in a new era of devices customers are passionate about and clamoring to have? Are you passionate about creating the operating system foundation to enable breathtaking experiences?...Windows across all device categories is readying for the introduction of 64 bit computing with the ARM instruction set (ISA). Bringing a new ISA to market involves working both broadly and deeply across Microsoft from devdiv to WDG to Server to Office and others depending on the scope of product target."

The big takeaway there is "Windows across all device categories is readying for the introduction of 64 bit computing with the ARM instruction set (ISA)". Additionally, Office and Server is mentioned as well, which is fascinating.

Some of the responsibilities of the job include:

  • Building the plan for ARM64 aligned with the Redstone wave
  • Identify the "big rocks" we need to move, solve, make it happen
  • Build the all up view of where we are, drive the schedule
  • Work to ensure the necessary hardware is planned for and delivered on time
  • Drive performance and compatibility goals, define and drive to key metrics

Likewise, the bit about "necessary hardware" being planned for and delivered on time suggests Microsoft is working on this solution for their own device range.

In some ways, this move to ARM64 is 100% completely expected. Microsoft was rumored to be working on an ARM64 variant of Windows RT before that OS got shuttered. Other companies like Apple with iOS and Google with Android are well into the 64-bit revolution for mobile. Apple's new iPad Pro gets solid benchmarks and great battery life due to its ARM chip the A9X; the iPhone has had an ARM64 processor since the 5s series. However, setbacks in chip manufacturing and Microsoft shifting gears with Windows 10 have added some speedbumps, but at least according to this job descriptions ARM64 Windows 10 is coming and slated for this year and likely by the Fall.

What would an ARM64 OS enable? At least for phones, we could see devices head past 3GB of RAM into higher ranges like 4 or 8GB variants. Toss in the rumored x86-to-ARM just-in-time (JIT) emulator, reported earlier by Petri and you could have a potentially powerful OS that not only gets decent battery life but could run some classic x86 apps. Even then, such a system could be employed on lower cost computers, tablets or even new categories, something that the Surface Book and Surface seem to push.

At this time, there are certainly many more questions than answers.

We do know that Microsoft is very serious about putting Windows 10 everywhere and part of the entails making the OS run all hardware whether it is the older x86 instruction set or, the newer ARM64 one. At the very least, we should see some interesting devices this fall as Windows 10 continues to expand to new categories.

Source: Microsoft Careers (opens in new tab); via @h0x0d

Daniel Rubino

Daniel Rubino is the Editor-in-chief of Windows Central, head reviewer, podcast co-host, and analyst. He has been covering Microsoft since 2007 when this site was called WMExperts (and later Windows Phone Central). His interests include Windows, laptops, next-gen computing, and for some reason, watches. Before all this tech stuff, he worked on a Ph.D. in linguistics, watched people sleep (for medical purposes!), and ran the projectors at movie theaters because it was fun.

  • Microsoft vying to take over the world. :)
  • #likeaboss
  • Microsoft being the boss: Coming Soon™
  • All They need is a car os now and then they got it all need to start adding more features and giving us polished windows updates...
  • I agree. They need to convince Tesla for example to get Win10 onto their dashboard. I did several test drives and concluded that the only two things holding me back are obviously the money mountain to climb to get one of these and the annoying dashboard. Especially the very slow google maps integration.
  • They already have a car OS that was in GMC cars, and they have been developing a new OS for the pass 3 years.
  • For whatever it's worth MS has been in cars for about 10 years (iirc).
  • #BlueAccidentOfDeath
  • What's better? A kernel panic? (Android). Or just don't get to see anything? (iOS) Mind you, the important part is on the ECU that is not running a consumer OS. Thankfully.
  • they did have a car OS with my Ford Sync but it wasn't as featuristic as an idroid but hey it worked
  • That car OS was called Kia Uvo also. I use it with my Zune HD daily.
  • Except that it didn't.  It was very widely criticized on release for being buggy, slow, and unintuitive.  Since then, Ford has updated the system, added buttons back to the console, and has decided to go for Blackberry based systems in the future. 
  • They are already using the blackberry system on many new cars/trucks (2016 F-150 as an example, any that advertise Sync 3).   Many people are saying the MS system was better.
  • After the lengthy Republican debate and you immediately wrote an article this long? Take a break man...
  • By Grabthar's Hammer, I will continue to work until no news is left! But seriously, with that small Rickman tribute, it is beer/bed time :P
  • He will forever be Gruber to me... And die every Christmas eve.
  • He has just gone back to his job as the Metatron.
  • :(
  • A Microsoft person talking about Hololens!
    And it also details battery life and some manufacturing things.
    Check this out! A Microsoft person talking about Hololens!
    And it also details battery life and some manufacturing things.
  • This is a cool video. Thanks for sharing. Good details on the device that weren't previously available.
  • Not getting much attention! lol
  • Mmmm... Beerbed
  • I would love to see a Raspberry Pi like device, Maybe RPi3, with a bit better processor running full W10. Connect it to any screen, and booom .. Instant PC. Also, i would like an evolved Continuum for "Panos Phone" like, true unification of W10M and W10, with W10M x86 being able to run like full W10, when connected to external screen and peripherals, all the while maintaining functionality on the phone. An Atom x5 or even x7 can get the job done easily.. That would be awesome :D
  • I would love to see a Raspberry Pi like device, Maybe RPi3, with a bit better processor
    Like the PINE64 running a quad-core ARM A53 64-bit processor that runs at 1.2GHz?  
  • I fully expect in time windows 10 will be supported on the pine and devices like it, even if just IoT core, I'll be happy.
  • It's done already look up voyo 2
  • You mean like the Intel Computestick? Or maybe a bigger one like HP's thin client?
  • Windows 10 mobile desktop addition.
  • Dream is going to be true....Hats off to Microsoft
  • Anyone have a Lumia 950 they'd like to give me?
  • Good question.
  • I'm pretty sure everyone here who doesn't own a 950 - including me - is thinking just that :)
  • Yeah please take mine :p
  • You can get one here:
  • Time to bury chromebook.
  • Agreed. I don't like the space they're digging in the education area. After all thats were lots of future users will come from.
  • Chromebooks will never take off. You can't download x86/x64 software. You definitely can't play PC games. Even Android has more software and functionality. All of the Google services can be downloaded and used on a Windows PC. The ONLY reason to get one is a hatred of Microsoft. Period.
  • Chromebooks already have taken off.  And they will be a force to be reconed with once ChomeOS and Android merge.
  • Cocaine is a hell of a drug..... Posted via.........deez nutz!!!!!!
  • Taken off? I've never seen one singel chromebook here in Norway.... Just Mac's and Surface Pro 3's everywhere!!!... And all these other chineese **** PC's....
  • Don't know about Norway, but in the US, and in particular in the education market, they are doing very well.
  • I don't think taken off is the right term, but they have certainly filled their niche. They aren't a bad device for what they are made for.
  • Lol. Yeah it's taken off so much that google chose android for the pixel c instead of chrome. Even google doesn't believe in chrome os
  • People said that about iPhones and Android devices.
  • Lumiabook.? Or edgebook?... Time to send chromebook to abyss.... The little space chromebook occupies in education must be eliminated. Google started with indirect campaign against windowsphone, and it's time for Microsoft to retaliate by attacking chromebook
  • You are trusting Microsoft not to surprise us with a slew of apps for Chromebooks?
  • They are already there, although they are just apps that take you to the online version of Office. Posted via the Windows Central App for Android
  • Thats basically what chromebooks are for 
  • Yeah, but going by my large district, schools with Chromebooks are only using Google's office-y apps.
  • I agree with that term - "office-y"; not exactly Office but office-y. :)
  • Good.
  • Android high end tablet....checked
    Chromebook... Checked
    Android Is next
  • It's time to make chromebook rival and make office 365 free for children. This will stop progress of chromebook... Microsoft bed to act fast before Android-chrome is merge
  • Sure, but did it really need to be said four times?
  • Aren't the HP Stream laptops Chromebook competitors? Posted via the Windows Central App for Android
  • I am surprised, Chromebook is still a thing? Last time I saw one in the open the user was furious that he had no internet and therefore could not use his "piece of crap". That was last Summer.
  • I just picked one up for £149. Quite pleased with it actually. You can work on documents off line, but agree they are not a lot of use without the internet. Mine was bought for using in the house anyway so not really bothered that it needs the internet. Posted via the Windows Central app
  • They are. Our large school district got boatloads of them just before school started last fall. Every student has a Google account, and all they see are Google apps. I'm surprised the district schools don't have Google flags on their poles.
  • That makes me sad. Schools are where the users of tomorrow come from and think of that generation being imprinted with google makes me worried. When ai have kids I either have to get the whole school they go to a complete selection of surfaces etc. or have a never ending argument with my kids. Ugh.
  • Windows 10 phone + Continuum + 8 GB RAM = the phone that can replace your laptop, desktop, tablet
  • *salivates*
  • LOL!
  • Not until we get a x86 phone, until then it will just be too slow to do anything serious.
  • I'd settle for ARM64 for now. That gets us the 8 Gigs of ram and Continuum with some horsepower. I'd be busy with that while they develope the x86 (x64) future.
  • When the products arrive on the market? 2020; 2023?
  • Fall this year maybe?
  • Article states this Fall....
  • Uh..... Just as how W10M was launched on time, right?
  • US only. New markets coming soon.
  • This should be there since the day one. Snapdragon 410, 808, 810, and others already are 64 bits, but the OS isn't. For sure Lumia 950 should have better perfomance and maybe even better battery life if it had ARM6 OS.
  • Yeah, because restructuring a whole company and developing on so many fronts can be done just over night.
  • iOS is x64 since 2013. LOL
    They had a lot of time, MSFT just don't care enought with W10M/WP.
  • His point still stands. Microsoft is working on multiple software projects at all times and unifying Windows has been going on for the better part of a decade. "iOS is x64 since 2013". Cool, Apple has two products that they constantly work on that aren't nearly as complex, their iPads and their iPhones. Sometimes they remember that they have a desktop OS but the two companies work on completely different scopes and have two completely separate aims. Besides, at this time, the perks for x64 on a phone are still minimal, lets see what happens when you add in a more powerful OS and features.
  • There's also the whole downside the binaries produced by 64bit compilers are much larger due to the larger address sizes, and they also take up more RAM. Therefore, unless you have more than 4GB of RAM or are constrained by some special requirement, there really isn't a point.
  • Doesn't mean their back catalogue of apps is optimized for it
  • My heart can't handle yet another leap of faith, sorry. Exactly half an hour ago I was finally able to sell off my Surface RT (I've sold yet another Surface 2 two weeks before that).
  • Guess what? No one is making anyone buy anything. Let alone the fact that there is nothing to buy yet.
  • You Can't pry my Lumia 2520 with keyboard from my hands. It still does 99% of what I need day to day. I even use it for presentations at work.
  • Ditto here! Love my SP2, SP4, 1520, and 950XL. But my 2520 has been my quick-draw weapon since it was released. Fantastic little beast.  
  • Lol also apple was rumored to be making their own arm port of osx as crazy as that sounds
  • I would love to have a surface phone with beefy specs and the ability to run all widows .exe apps. A better idea will be to add a gpu with the continuum dock. Gaming in a whole new level.
  • A gaming dock for a phone ... Well hell yes.
  • Dude.  That's actually a pretty excellent idea.
  • The dock should be made with GPU upgrades in mind and manner even a hard drive Posted via the Windows Central App for Android only because the screen on my 1520 broke.
  • What is Intel's fate?. Will this move reduce intel's revenue or limit Intel processors to high end devices ?
  • I shuddered when I read that windows RT was shuttered.
  • Hey, don't hold the editorial staff to such high standards...
  • I guess this is Apple's future plan for iPad pro. It's a good move by Microsoft before Apple come up with this same idea.
  • *Reinvent
  • Yeah please comment on the same post 10 times :D
  • Windows 10 Mobile x86 doesn't seem like a good idea.
  • Why?
  • Interestingly, the WM10 emulator in Visual Studio takes an x86 build of the app you're testing.
  • It does? Does X86 apps have more robustness than ARM based apps?
  • Finally! Can't come soon enough!
  • Well knowing Microsoft, I'm sure they're gonna try and come up with a name for these types of devices. I could see them coming up with something on the nose that incorporates the word ARM. Something like- Windows Across a Range of Machines or W.A.R.M. for short. I mean, if they can come up with something like 'RT', W.A.R.M. might not be that far off. With that being said, bring on the W.A.R.M. devices!!
  • Not cool.
  • I see what you did there- W.A.R.M., not "cool". 
  • They could use the name Edge OS or Cortana OS for the name of these devices Posted via the Windows Central App for Android
  • I think I see what you're going for there, but I think Microsoft would want Edge and Cortana to be more fully formed before they started naming things after them. With a chromebook, people have an expectation based off of the chrome name, and while I personally haven't had any issues with Edge, from what I understand, it isn't up to par with Chrome as a browser yet, nor is Cortana as powerful as Google's voice assistant (in some ways) just yet. 
  • AMD just made its ARM64 CPU announcement today.   Another big market is the Synology/NAS type market.  A number of these run Atom or ARM.  Obviously all ARM NASs use Linux. 
  • Off topic but since last oct i havent bn able to download or update a single app! The store shows error 99% of times and when it works none of the apps can be downloaded! I hard and soft reset my phone twice but no success!changed regions, formatted sd card many times and switched off and on phone . Am fed up with windows worked fine for a year but is pathetic now! The customer care guys couldnt help either.ive ran out of options , using win 8.1'on phone. Is anyone facing the same problem.please help!
  • x86-to-ARM JIT would sap quite a bit of power. Hope they pack a hell of a battery with that.
  • So does this mean it's best to ignore/skip the current line of the 550, 950, 950 XL surface pro 4, surface book 1 (and upcoming 650 and 850 devices?) devices and go for this next platform?
  • If you keep waiting for the next big thing you will ALWAYS be waiting and never enjoying. Take the plunge.
  • If you can wait roughly another year, sure. But right now the current Lumias, especially the 950, are extremely good phones. Win10M on the other hand still needs some work though. If you current handset suits you I recommend waiting.
  • The 950 is not an extremely good phone. It might be the worst smartphone of all time.  Windows 10 mobile is horrible.
  • You just parroting, or do you actually have one?  Cuz around here there are 10 parrots for every unsatisfied 950 owner. Sounds like a choir, but it't starting to die down finally.
  • Yep.  I'm one of those suckers who actually bought one.  It's horrible in nearly every way.  Most of that comes down to Windows 10 Mobile just not actually working right. And the four hours of battery life is a joke.
  • Care to elaborate on that? My 950xl dual sim does an outstanding job, can't think the 950 does a bad job either
  • > My 950xl dual sim does an outstanding job I don't believe you.
  • Well, in fact it does. ​No freezes, no reboots, no lags. I just try to avoid that peski, Battery draining mess of a browser. I remove the charger around 7 in the morning and come home at 19:00 with 40% left while i used it all day (Music streaming all day at work, Netflix on the way home, reading news on the way to work, wrinting some word files, making notes, checking excel files). Not using it for gaming though. So I personally do not get the hate. Waiting eagerly for the display dock so I can do even more with it at work through continuum and getting a miracast adapter for my home TV. But well, disbelieve me all you want; I am genuinly happy with it.
  • I think with windows 10 mobile upgrade coming to my lumia 1520 I can wait for another year. I'm already very satisfied with what windows phone 8.1.1. can do for me now. My 1520 and my apps suffice and I love the camera. It's good. If I really have to bring it down to one thing I really want, its landscape support for the start screen.
  • This is exciting. I was a supporter of Windows RT on day one. It is sad that the world didn't adopt it. There is the future.  Win10 Mobile :D yay i remember my Win mobile 6.0 device.. 
  • Well as unimportant as retail software market was then the retailers clinged to that reason to not get a rt slate
  • This basically confirms what Surface Phone will be. *drools*
  • Hey Microsoft, why did you kill off Windows RT when it was really where you (and the whole mobile spehere) are headed? x86 chips are too inefficient in their current iteration to be considered a serious contender against ARM as a SOC. All RT devices are quickly becoming redundant thanks to the current refusal to update 8.1 RT to W10 (on ARM) or provide a universal app framework update, facilitating W10 based apps in the store.
  • Except that ARM chips are far less powerful then current Intel ones.  Intel have a 2 year technology lead on their rivals, Intel have been moving into the mobile sphere aggressively in the past few years, now we are at the point where there is just no benefit in supporting anything but a x86 chipset because we could finally have one single chip to use between phone, tablet and PC.  At that point Coninium becomes a serious asset, and ARM based machines are left trying to emulate to get the same benefits. So supplying yet another incompatible RT OS is just a total waste of resources, this effort will be dead on delivery.
  • Is there an X86/X64 variant of SnapChat on Windows? Nope? Then good luck getting 99% of my generation on board. Most of my generation don't give two hoots about X86, they just want those apps that we don't have. Now I love my Lumia 950 and the app gap, while it does bother me, isn't enough to shunt me off the platform (for now). Most of my generation aren't so forgiving of the app gap though. And the apps they care about aren't on Windows X86/X64. So it still won't get them on board. Though I'm looking forward to using Continuum in more apps on my Lumia 950.
  • All depends on how you look at it at least with arm its a more set in stone spec. to code for across various devices unlike intel which can get messy if OEMs choose to ship with limited amount of ram storage
  • Does it mean I will get Windows 10 on my Surface 2? :-) Seems logical.
  • Lets hope so
  • Well considering NVIDIA dropped support for all tegra processors it may not be a great experience
  • I was left behind with Surface RT - that would be amazing but I guess there will be something what will make it technically imposible :/
  • So Windows 10 a PC OS will work on something like Snapdragon 820?
  • Yes minus support for 16bit applications
  • JIT emulator?
  • bring it on..
  • A year later...
    Surface Phone 2 (coughs)
    9th Generation Intel Core M3 3.0GHz with IntelTurboBoost 3.2GHz
    8GB RAM LPDDR5 (€€€€)
    16GB RAM LPDDR (€€€€€)
  • Hmm, wonder if there is any tie-ins to project midori.
  • Another empty windows RT 64, nobody want that microsoft. You are really lost in this industry. Just make with intel some cool atom for phones, you have modernUI, UApps and with continuum docks that can switch to desktop windows. You can add some gaming GPU into that docks too. That's the future.
  • Wrong. Laptop and tablet makers want the processor choice. Continuum is great, but what if you had the ability to store x86 programs on an external drive plugged into your dock and use them with full functionality. Google is working on this, they are combining Android and Chrome OS to make their pixel C tablet worthwhile.
  • Apple is even trying to directly port osx to arm
  • But this win can not run x86 programs read article, emulators never works. Do not understand what this have anything with storage.
  • Its a shame it might be too late for my surface rt 2.
  • I thought the windows RT thing was dead and buried, why produce yet another incompatible platform?  Technology wise they are behind Intel so there is no benefit at all in that area. Yet more resources wasted that could be put to use producing products people actually would be prepared to pay for, the continium idea is the best new one they have had for ages, it could well be the trojan horse to get windows phone into a lot more peoples hands.
  • Leave that ARM stuff alone and focus 100% on enhancing the tablet mode and desktop mode on Windows 10. And make a killer Surface phone using Intel chipsets.
  • Snapdragon 810 is already a 64-bit architecture. The real information is the use of 64-bit ARM with x86 applications. Cell Phones can be full PCs and PCs makers would then be able to choose either x86 or ARM for their devices without hindering use cases.
  • So you're saying MS is still behind the competition? Apple and Android has been using 64bit architecture and now MS is just in the hiring phase for it? Man! No wonder their mobile division can't move forward.
  • Serious question, how many iPhone/iPad and Android apps take advantage of the 64 bit architecture and what are the current discernable advantages on your smartphone?
  • MSFT shareholders will force Nadella to shutter Xbox and windows 10 mobile by Easter.
  • Lets hope not, seeing the potential of the iPad Pro and its A9X capabilities with more performance and better power efficiency than a 2 year old Intel Core i3 4005U/4030U, gives us an idea that Autodesk, Adobe and other software giants are transitioning from x86 to ARM. What this means is than in a few years, the Pro design software made for the Apple Pencil + iPad Pro won't be available for x86, which could mean a disadvantage for Microsoft if they don't implement Windows 10 desktop on ARM. With iOS app compatibility for Windows 10, this means in a few years, both the Surface Pro and the iPad Pro can have the same applications. IMO this is a homerun for Microsoft.
  • Xbox and mobile aren't going any where any time soon. The future is mobile and xbox gives them a foot hold in the living room. Granted in the past the messaging has been mixed but now it's gaming first and foremost.
  • Wow! If this happens I can say goodbye to Android and come back home. If Microsoft can keep the same 20mp lens with a slightly bigger sensor and add a xenon flash with the exceptional hardware everyone's expecting for the Surface phone then this will....oh wait, probably another exclusive. I'll wait and see what happens. One picture at a time -- LG V10
  • Does this suggest the move to 64-bit for Mobile?
  • RT is back!!
  • It's a little disheartening when i think that someone in this capacity isn't already employed by Microsoft.
  • So, when did Windows RT get 'shuddered'?
  • Awesome additional news. How do I sign up for insider testing on my Surface 2?
  • I can see it now... "One Device, Infinite Possibilities™ "
  • Really wish Microsoft would just make 1 thing work good before moving on to other things. Everything they come up with is superior in CONCEPT, but the execution is just pathetic. There's a lot of things in W10 and W10M that just drive me nuts. More work load just means more bugs for the next 5 years and as a professional that uses his computer for real work, this is really off putting.
  • MS has over 100,000 employees. Can you explain what you expect a company of that size to accomplish by only working on one thing at a time and never looking forward to their next move? And please don't say that Apple or Android don't have software problems because they do as well. If Windows 10 is so problematic, no one is holding a gun to your head and keeping you from downgrading to an earlier version of Windows.
  • Can we just get an Intel based Windows phone plz...
  • A new Life for Surface RT?
  • Does it have a ARM64 processor?
  • 64bit is available on iPhone since 2013 and android 2014, I guess Microsoft likes to come second on stage!
  • I'll ask you the same thing, I asked someone else above. How many iPhone and Android apps take advantage of it and what are the current discernable differences on the phones with 64 bit?
  • YEp,  iphone has 64bit,  and nothing to take advantage of it....same ole same ole from apple...baffle them with bullshit....
  • Their interview is insane. So is Google's. I didn't even feel that bad when I didn't make the cut for either.
  • What does this potentially mean for current generation Lumias - perhaps they're not completely obsoleted by an Intel phone because they could still run the x86 emulator? I wonder what performance would be like running something like Visual Studio or Eclipse IDE on a SD808/810 with 3GB ram
  • is this mean we can run win32 / exe files on the lumia 950 or 950XL ?
  • I bought a windows RT tablet from Microsoft. this will be a flop, don't trust them to support it in the long term.
  • Everyone is so focused on ARM64 being used in smaller consoumer devices (Phones/Tablets). I wonder if this posting is more for Windows Server??
    Search "HP MoonShot" for some more information. It would appear that HP has servers that are running with ARM64 processors to allow decent power, with little energy/heat. This would result in HUGE savings for companies that don't necessarily need the power of Xeon or Opteron CPUs in their servers.  This would also allow those same ARM64 servers to run essentially the same OS as their X86/X64 systems, helping to keep support costs down.
  • ARM64 is definitely aiming for the cloud (see also and  Windows had better be there and it sounds like it will be.  And I would welcome it - the more the merrier.  That said, Microsoft lawyers and Windows licensing may be more of an impediment to adoption than the pace and timing of MS software development (have you even tried to read the licensing gobbledygood for Virtualized Windows?  That alone is enough to drive people to Linux) ". . .we could see devices head past 3GB of RAM into higher ranges like 4 or 8GB variants. . ."  Yes, but, this doesn't have that much to do with the width of registers than hold pointers.  Caldera had a 32 bit ARM with a 40 bit physical address space awhile ago.  X86 fans may remember that Intel sold 32 bit Pentia with a 36 bit physical address space.  Yes, one 32 bit process can't make use of all the memory at once.  Not an issue for most applications. Also the obsession with X86 vs ARM performance is misplaced.  For phones, phablets, tablets, netbooks, notebooks and desktops, the performance of many frequently performed actions depends more on things like memory speed, cache size, bus architecture and accelerator performance (etc.) than CPU performance.  Smaller cores (and ARM cores are smaller for a comparable level of complexity - w/wo OOE, w/wo register renaming, etc.) mean more room for cache.