Retina Display: Scrolling & UI Performance

With the first Retina MacBook Pro I noticed UI performance in certain applications degraded considerably compared to previous, non-Retina MBPs. Browsing my Facebook news feed in Safari and scrolling down as well as just scrolling through a long email thread in Mail both caused frame rates to drop below 30 fps. Performing the same tests on my 2011 15-inch MBP yielded UI frame rates closer to 60 fps.


13-inch rMBP (left) vs. 15-inch rMBP (right)

The move to Mountain Lion improved UI performance, but it's still an issue. Switching between Retina and non-Retina MacBook Pros results in a very noticeable difference in UI frame rates, especially in problematic applications.

Apple does a lot of CPU and GPU work to make OS X look like OS X. Scaling the workload up from 1.76 million pixels to 4 and 5 million pixels creates additional work for both the CPU and GPU that neither chip vendor had planned on. Apple had to replace some fixed function code with general purpose CPU and GPU code to achieve consistent image quality in enabling Retina, which obviously has performance implications.

Next-generation GPUs should do a better job of driving these ultra high resolution displays, but today it looks like our biggest bottlenecks are software and single threaded CPU performance. In every situation where UI frame rate drops significantly on the rMBP, the offending application usually ends up consuming 100% of a single CPU core. This is true in Safari, Mail and other applications where I notice drops in scrolling frame rate.


The worst case UI perf

The worst case performance I recorded on the 13-inch rMBP was 16 fps when scrolling in Safari with Facebook loaded at the 1440 x 900 scaled resolution setting. Minimum frame rate at the default best for Retina setting ended up being around 18 fps. It's distracting and a clear regression from other, non-Retina Macs. That's the lowest performance you see, but not everything falls into that range. Scrolling down the AnandTech front page for example happens at around 40 - 50 fps at the 1440 x 900 scaled resolution. Other animations will happen as high as 60 fps, although you typically notice when things are slow not when they're performing as expected.


The better case

The 13 I'm testing had demonstrably lower scrolling performance than my 15-inch rMBP, but I believe that has to do with the difference in CPU clocks more than anything else. My 13 uses a 2.5GHz Core i5 that can turbo up to 3.1GHz, while my 15 has a max single threaded turbo of 3.6GHz - an increase of 16%. There's also the fact that the 15-inch model features a quad-core CPU, leaving you with more idle cores in the event that you're actually doing more than just scrolling all day. I suspect the combination of these two things is why a lot of folks perceive the 15-inch rMBP to deliver faster UI performance.

The 15-inch model does have a discrete GPU, however I didn't notice a big performance difference in UI frame rates when I was on integrated vs. discrete graphics. I do believe that a lot of the present issues are related to Apple not GPU accelerating more of the drawing pipeline and as a result, single threaded CPU performance suffering under the load of 4 and 5MP displays. Intel (and AMD) design their CPUs for the types of workloads most of their customers will be running. The vast majority of the market isn't running OS X with 4MP+ panels. A lot of this is related to OS X itself, as you don't have the same scrolling issues under Windows. As we saw in our Surface review, simply making an application (or in this case, an OS) look a certain way can eat up a good amount of CPU time.

There's not much you can do here other than wait for faster hardware or buy the fastest CPU available on whatever system you're considering. Single threaded performance will scale linearly with CPU clock speed, so higher clocked CPUs should deliver smoother scrolling performance. Ultimately just scaling CPU clock is an inefficient way to solve the current UI frame rate issues. Future revisions of OS X will likely shift even more UI workload to the GPU, plus we'll see new microprocessor architectures that will perform better with these types of workloads as well. The only issue is I don't know when either of these things will happen. Haswell should bring a good increase in IPC and maybe even a slight increase in frequency, which will definitely help.

What we'll need however, without any significant changes to OS X is an outright doubling of single threaded CPU performance. In the worst case scenario that could mean that we won't see UI frame rate fixed for years. I doubt it'll be that long, if I had to guess I would say that Haswell will bring a good improvement and around the Broadwell (2014) timeframe is probably we'll see things really get better. I don't have intimate knowledge of Apple's OS X roadmap and I also don't know the instruction mix that's causing this behavior so I can't really say anything for certain, I'm just speculating.

The 13-inch Retina Display in Numbers USB 3.0 Performance
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  • nerd1 - Tuesday, November 13, 2012 - link

    I just cannot understand Apple's spec selection for this laptop.

    They are selling this as 'Pro' laptop, with fixed 8GB ram, 128GB starting storage space (and HUGE overcharge for slightly more useful 256GB) and no external graphics.

    I don't think this is any better than recent full-HD ultrabooks from other brands, usually around $1000 price tag recently. 1080p is more than enough on 13" screen, and they provide cheaper storage upgrade option (256GB mSATA drives are now cheap around $200), and some even has external GPU. And face it - 2.5Ghz i5 won't give a huge performance edge over 1.8Ghz i7 ULV with turbo boost for most applications.

    Yes, I know it will still sell like hotcakes.
    Reply
  • lukarak - Wednesday, November 14, 2012 - link

    That`s the only problem. Simply put, a dealbreaker, especially for mac users , that inherently have an above average need for virtual machines.

    Everything else is expected.
    Reply
  • bji - Thursday, November 15, 2012 - link

    Anand - the image retention flaw on the 15 inch rMBP is a real issue. I have written you several emails asking if you'd like to address this using your testing tools but never received a response. You haven't acknowledged this issue in this review either.

    Is the 13 inch rMBP subject to the same image retention flaw?
    Reply
  • bji - Thursday, November 15, 2012 - link

    WHOOPS - I am wrong. You did address this, I just didn't see that paragraph somehow.

    It would still be great if you used the tools at your disposal to analyze this. There are reports that the heat of the display (air conditioned versus warm room) have an impact, and of course it's well known that only LG displays suffer this issue. Having all of that confirmed by a reputable reviewer would be great.
    Reply
  • edgarperez - Saturday, November 24, 2012 - link

    I am trying to decide on a replacement for my 2gb mba 13" . The UI references including "Also if you're looking to minimize UI frame rate issues as much as possible you're going to want the upgraded CPU (although that still won't eliminate low UI frame rates)." truly scar me away from the rMBA. I am on my machine 12 hours a day regularly. the thought of the UI lagging scrolling on applications This is not something i noticed when i looked at the machine in the store but certainly something that would drive me batty once i have noticed it. I think I am going to have to think more about the MBA vs. the MBP non retina and pass on the retina for now. Reply
  • Zink - Wednesday, December 05, 2012 - link

    It's not really lag, just low frame rates. It works just as fast as it should but looks a pit more choppy while moving. Reply
  • marioyohanes - Friday, December 07, 2012 - link

    Well, I'm one of those people who always complaint about "Pro" in 13" MBP/rMBP, it should be named MacBook, without Pro because it is not a Pro machine. And maybe we could get lesser complaint on Mac App Store comment section for 3D games just because they thought 13" MBP can do 3D game.

    As for 13" rMBP, here my two cents after using this thing for a month (I got it for free anyway, so...):
    - 8GB RAM is not an issue, period! You just trolling saying it needs 16GB! You just don't run 2 VM, 100megs AI files while running FCPX on this machine, you just don't do that.
    - 128GB SSD for $1799 laptop? This is annoying! Seriously? 128GB? And yet you still calling it a Pro? I'll be damn!
    - Display is awesome, super awesome, even though, I prefer to have 1440x900 resolution over native retina. The only thing I hate from 13" MB/MBP is the resolution barely usable for professional work. However, if you're iOS app developer or UI designer, this thing rocks! No more scrolling madness for testing app on retina simulator or designing retina artworks in Adobe!
    - UI performance is not an issue, at all, some websites simply just another prove of bad programming. And retina aware apps are widely available, if they're not updating their app to be retina aware until first half 2013, it means the app is either no longer under development or its developer simply not serious selling Mac apps.
    - Gaming or anything 3D? Forget about it. Unless of course, by gaming you meant Angry Birds, but for me, gaming is stands for Steam, AC3, Diablo 3 and the list goes on.

    So who is this for? Professional who does a lot of work developing or designing retina UI but hates 15" rMBP portability. Or, it could be great for business professional, you'll be thank to its retina display for saving your eyes for working too long in front of your computer.

    This is not for me, obviously, I switched back to my 15" rMBP after a month. This is well overpriced on my opinion, but then again, no competition whatsoever. And yes, please stop telling me ultrabooks $1000 etc, the closest ultrabook price with this thing is cost more than $1400! But then again, if you're making money with your laptop, why bother with price, as long as its beneficial for you to have this rMBP (also works for boosting confidence), just buy it and don't look back. Haters will be haters, don't listen to them.
    Reply
  • .Chris. - Tuesday, December 11, 2012 - link

    Grate in-depth review wish I found this 2 weeks ago
    I bought a maxed out air then sent it back after seeing the retina display in store.
    Since then I’ve been trying to decide if the upgrade to the faster cpu is worth it for the rMBP. Sounds like it is and as I am paying education prices which brings it in at £1383 (which still hurts but not as much as £1609)
    Reply
  • AirieFenix - Monday, March 25, 2013 - link

    I would love to see a 13-inch "non-Retina" Macbook Pro with some of the goodies of the rMBP. For instance, I need the Ethernet port (yes, there is an adapter, but I'd rather prefer o have it out-of-the-box); I also like the battery life on the non-Retina model, and to have upgradable hardware is almost a must-have for people that don't buy a new notebook every year (for instance, me).

    In the other hand, I don't use the DVD drive on my computers since... I don't even remember. And the 1280x800 is a low resolution right now.

    But most important, I'd rather prefer to have a consistent fluidity through all the UI than more than a lot of pixels (yes, it's a nice display, but I'm not a photographer, it isn't a must-have to me) and the price. The price of the Retina model is just too absurd.

    Why don't make a 13-inch Macbook Pro with Air's display (a not Retina, but still good) and without DVD-tray (although I can live with it, would be nice to have more space for battery life)? That would be my dream machine.
    Reply

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