Performance

There are two aspects to Surface’s performance that we need to discuss: the user experience and then quantitative performance metrics.

User experience is equal parts hardware and software, and this is one area where Microsoft really delivered with Windows RT. Frame rates are solid and stable, easily delivering what appears to be 60 fps for UI transitions. If you try to push the hardware too much, RT seems to completely drop animations vs. animating choppily which seems to be the right tradeoff to make. Overall that doesn’t seem to happen all that frequently.

Scrolling down web pages is also very smooth, although you can get IE to behave very jittery if you hold your finger in the wrong place on the screen while scrolling. There are some rough edges with the RT UI but overall it’s still very good.

I’d say in terms of smoothness of UI, Windows RT on Surface is much more like the iPad (or Windows Phone 7.5) than most Android tablets. Jelly Bean does complicate things as it really fixes a lot of the UI performance issues that hampered Android. Even then I’d say Surface’s UI responsiveness is among the best.

Application launch times are another thing entirely. Nearly every application I launched took longer than I would’ve liked on Surface. I can’t tell if this is a hardware issue or a software optimization problem, but application launches on Surface/Windows RT clearly take more time than on an iPad. I timed a few just to put this in perspective:

Application Launch Time Comparison
  Boot Web Browser Mail Maps Games Center / Xbox
Apple iPad (3rd gen) 32.0s 1.0s 2.4s 1.1s 1.9s
Microsoft Surface 27.7s 2.6s 7.1s 5.0s 5.0s

Now once apps have been launched, switching between them using Windows RT’s excellent multitasking system is just awesome. Apps fly in with little to no lag and the process is just great.

The only other user experience issue I have with Surface has to do with CPU utilization when using Office 2013. Surface, like all Windows RT tablets, comes with a free installation of Office 2013 Student & Home Edition. Surface also happens to use a quad-core NVIDIA Tegra 3 SoC, featuring four ARM Cortex A9 cores running at up to 1.3GHz. At least for the Cortex A9 generation, I don’t know that Microsoft could’ve used anything slower. Simply typing quickly in Microsoft Word maxes the single threaded performance of Tegra 3’s ARM Cortex A9 cores. I’ve seen CPU usage a high as 50% when typing very quickly, but mostly it tends to sit between 20 – 40%. Switch to notepad and max CPU utilization drops to sub 10%. This says more about Office 2013 than the performance of NVIDIA’s Tegra 3, but there are not a whole lot of spare CPU cycles to go around with Surface.

This brings us to the next part of the performance discussion: quantitative performance analysis. Windows RT/8 will likely bring balance to the tablet benchmark scene, but all of the folks currently working on benchmarks are targeting a late 2012/early 2013 release. We will eventually see everything from PCMark to GLBenchmark ported to Windows RT, but until then we’re left in the same situation we have under iOS: relying on JavaScript benchmarks to characterize performance.

With only two Windows RT tablets in our possession (ASUS’ VivoTab RT and Surface), this section would be pretty bare. To rectify this problem I phoned a friend who let me borrow a soon to be released Clovertrail (Atom Z2760) based Windows 8 tablet. To avoid getting in trouble with the specific manufacturer of this tablet I’ll refrain from posting photos or calling out the device by name, but we’ve talked about it on the site before.

As a recap, Clovertrail is the x86 alternative to ARM for Windows 8 tablets. The Atom Z2760 integrates two 32nm Saltwell cores running at up to 1.8GHz. Each core is Hyper Threaded so the entire SoC can work on four threads at a time, similar to NVIDIA’s Tegra 3. The GPU is Imagination’s PowerVR SGX 545 running at 533MHz. The SoC features a dual-channel LPDDR2 memory interface. NVIDIA’s Tegra 3 has a single channel LPDDR2 interface running at a 1500MHz data rate in Surface.

On the user experience side alone, the Clovertrail tablet is noticeably quicker than Surface. Surface isn’t slow by any means, but had it used Atom hardware it would’ve been even more responsive.

Putting all of this into numbers, we have a collection of JavaScript performance tests, some of which were used in the iPhone 5 review. Note that all of these tests were run using IE10 in Windows RT/8 thus making the comparison less about software and more about hardware differences:

JavaScript Performance
Time in ms (Lower is Better) Kraken SunSpider RIA Bench Focus
Intel Atom Z2760 33855.7ms 714.9ms 3872ms
Microsoft Surface (Tegra 3 1.3GHz) 49595.5ms 981.1ms 5880ms

Across the board Clovertrail manages a 30 - 50% advantage over Tegra 3. Granted we’re not looking at power consumption here, but the Clovertrail tablet I’m comparing is even smaller/lighter than Surface for what it’s worth. We’ll have battery life numbers for it in the coming weeks.

Principled Technologies, apparently featuring some of the same folks who were responsible for building the old Winstone benchmarks from over a decade ago, actually put out the first cross platform Windows RT/8 benchmark with some help from Intel. Despite Intel’s influence the test appears to have no native code, instead relying on just a heavy workload of large images and videos for its tests.

TouchXPRT 2013
Time in Seconds (Lower is Better) Photo Enhance Photo Export Video Transcode MP3 Transcode Photo Slideshow Creation
Intel Atom Z2760 210.83s 73.93s 53.91s 98.66s 85.81s
Microsoft Surface (Tegra 3 1.3GHz) 306.12s 116.36s 87.27s 160.99s 125.06s
ASUS VivoTab RT (Tegra 3 1.3GHz) 312.14s 109.89s 89.69s 155.84s 122.65s

The large files used in the workload do a great job of showing Atom’s memory controller advantages over that used by the Cortex A9. The results here likely overstate the Clovertrail performance advantage a bit (I’m not sure how much 1080p video transcoding you’re going to be doing on Surface as compared to web browsing) but the results tend to agree with what our browser based JavaScript tests show: Intel’s Atom Z2760 is considerably faster than Tegra 3 here.

I understand that Microsoft needed a good launch vehicle for Windows RT, however I really would have liked to have seen an Atom version of Surface. An Ivy Bridge version is in the works, but it’s also a bit larger. An Atom version could retain the same chassis size/weight, but deliver tangibly better CPU performance. Again we’ll have to wait to see what battery life looks like for these Clovertrail tablets before really deciding whether or not Atom would’ve been a better fit.

Battery Life Windows RT
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  • sviola - Wednesday, October 24, 2012 - link

    Care to source the claim that A6 performs the same as x86 core processors per clock cycle? Reply
  • blandge - Wednesday, October 24, 2012 - link

    "A6 is as fast as Intel per clock cycle. (and yes: I understand that A6 is dual core and intel is quad + clocked much higher. But the fact is that A6 is as fast per clock cycle. ARM will replace X86)"

    This simply isn't true. The A6 scored 908ms on the SunSpider browser benchmark and a 2700k scores about 135ms (Lower is better). That's about 6x better, and SunSpirder is a SINGLE CORE benchmark.
    Reply
  • Brainling - Wednesday, October 24, 2012 - link

    Are you serious with this about the A6? The A6 is NO WHERE NEAR as fast as full on Intel silicon. It's not even in the same ballpark. Maybe if you're comparing it to Atom?

    An Ivy Bridge full silicon CPU is in another league over the A6. Of course, they aren't meant for the same purpose. Even taking the faster clocks in to account (~4x the clock speed), the Ivy Bridge regularly scores 6-7 times the execution scores of an A6 in synthetics. That's not pure clock speed, that's also a flat better CPU.

    I swear...some of this stuff is just mind blowing. What in the world would have ever made you think an A6 was "clock for clock" as fast as Intel's best offerings? Also, the XBox 360 doesn't use an Intel CPU or an x86 CPU...it's a Motorola PowerPC. Might wanna check your facts next time.
    Reply
  • Kevin G - Tuesday, October 23, 2012 - link

    A typo: "Microsoft offers Touch Cover in six colors black, white, magenta, cyan and red." Not sure if a color is missing or you meant five (though five pictured).

    Anand, you've been taking the Surface around judging the examples in the article. Any chance it was with you during the iPad mini event? I can image the looks being worse than when you tried to make a call at the iPhone 5 event.

    "Simply typing quickly in Microsoft Word maxes the single threaded performance of Tegra 3’s ARM Cortex A9 cores." It does seem odd that one of Surface's biggest selling points on the software side is a self inflicted wound. Office should be the premiere application for MS to show case, not bloatware that'd deserve to sit in the sloth exhibit at a zoo. Was Office even usable?
    Reply
  • Ryan Smith - Tuesday, October 23, 2012 - link

    Apparently we can't count today. It is indeed five colors, not six. Reply
  • ssiu - Tuesday, October 23, 2012 - link

    Finally, some objective Windows RT versus Windows 8 Atom tablet performance comparison on the net -- thanks anandtech. Definitely no reason for me to consider Windows RT. Reply
  • Zink - Tuesday, October 23, 2012 - link

    Yep this is silly. The only reason for RT is to let OEM's compete <$500 with Apple and to emulate other walled garden ecosystems.

    Atom should have been launch hardware for a better user experience. Hasn't Apple success shown that UI is #1?
    Reply
  • dagamer34 - Tuesday, October 23, 2012 - link

    Basically it seems like Microsoft built a rather competent product, and when we see Windows RT tablets with stronger hardware like Tegra 4 or S4 Pro, it should be a great experience.

    Considering this is Microsoft's first hardware computer, they could have done a LOT worse, and there are some things you only learn by actually shipping a product. For a 1st gen release, that's pretty good.
    Reply
  • shompa - Wednesday, October 24, 2012 - link

    Thats is one of MSFT problem. Since they control the hardware, we wont see the crazy Android/PC hardware wars. How long time for MSFT to write drivers/support Tegra4 or any other fast SoC?

    Just look at Windows Phone. Nokia have the killer "Pure View" and MSFT don't support it.
    (And thats is why Nokia will die with only MSFT support)
    Reply
  • notanakin - Tuesday, October 23, 2012 - link

    "Microsoft’s talents not as a software developer nor as a parts assembler are what make Surface great here, rather its design and manufacturing intuition."

    Er, so what is it that makes Surface great here? Almost sounds like the less talent you have, the greater the product. (In that case, please contact me for insanely great product designs.)
    Reply

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