Why is there scroll lag on rMBP, but not on iPad 3?

Discussion in 'MacBook Pro' started by YoYoMa, Jul 3, 2012.

  1. YoYoMa macrumors 6502

    Joined:
    Aug 3, 2006
    #1
    Any thoughts on this? iPad is much less powerfull, yet there's definately no lag when scrolling through dense websites that I've noticed. Are we sure that the
    lag is indeed a hardware limitation that can't be completely overcome with software fixes?
     
  2. charlieegan3 macrumors 68020

    charlieegan3

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    Feb 16, 2012
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    U.K
    #2
    While i see your point, the iPad and the rmbp are totally different machines, also the iPad3 worked from release? (it didn't need a major update to sort out issues)
     
  3. jbud72 macrumors member

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    Mar 21, 2010
    Location:
    Miami, FL
    #3
    I think this is a good question. I am curious as well, if anyone has any insight
     
  4. iamrobk macrumors member

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    Jun 30, 2012
    #4
    My guess is that the iPad's GPU is used for most rendering instead of the CPU (which the rMBP uses). ML chages the rMBP so that the GPU is used more, which is why it makes it a lot smoother in general.
     
  5. melterx12 macrumors 6502a

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    Jun 22, 2010
    #5
    This is probably because the "driver software" (in quotes because iOS doesn't actually use drivers) that controls the iPad 3's hardware was written from the ground up for that specific hardware, possibly using Assembly (not sure).

    This allows for a very high level of optimization, similar to how an Xbox 360 or Playstation 3 is able to play modern games at 60fps even though they have pretty outdated hardware by today's standards.

    I'm sure Apple will release software updates that will remedy all the lag issues sooner or later.
     
  6. iFanboy Guest

    #6
    There is no scroll lag on the rMBP

    The number of people complaining about lag are dwarfed by the number of people not complaining and enjoying their device.

    HTH.
     
  7. melterx12 macrumors 6502a

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    Jun 22, 2010
    #7
    I notice lag, not in scrolling but in other things such as resizing a window.

    However it doesn't really bother me at all so i'm not complaining.
     
  8. leman macrumors 604

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    Oct 14, 2008
    #8
  9. robotkiller macrumors 6502

    robotkiller

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    Oct 25, 2009
    #9
    I wish that was correct. Truly.
     
  10. leenak macrumors 68020

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    Mar 10, 2011
    #10
    I have an iPad 2 and it has some scrolling issues sometimes. Not sure the iPad 3 and it are that much different (better display and better processor but still shouldn't be that drastic of a difference). I don't plan to get another iPad for a few years so I didn't keep up with the iPad 3 so not sure if those issues don't show up in the 3.

    ----------

    There was a poll, I can't find it though. Basically the summary was that people who see a scroll lag think that those that don't are not as perceptive or something...

    Any lag I have seen is very minimal and seems to be on websites that have the same issue no matter what computer you are on. That to me doesn't point to the computer.
     
  11. Sambo110 macrumors 68000

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    Mar 12, 2007
    Location:
    Australia
    #11
    Is the scroll lag less on the 2.6/2.7 ghz model compared to the 2.3 ghz? It would make sense if it was a CPU problem.


    I just had to correct you by saying most games DON'T run at 60FPS. The few that do look really bad (CoD), and usually run at low resolutions.
     
  12. ender21 macrumors 6502

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    Jul 15, 2010
    Location:
    Southern Cal
    #12
    I don't know about anyone else, but I occasionally get lag on the ipad3 as well. It's not bothersome, but it is noticeable and repeatable on the same or similar content.
     
  13. robotkiller macrumors 6502

    robotkiller

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    Oct 25, 2009
    #13
    I'd like to think it's in my head. Maybe it is - I've thought that maybe the higher resolution plays tricks, visually, with the perception of smoothness. This seems too tortured an explanation and it's refuted by the iPad3, which is insanely smooth. For the record, I don't think that the computer is defective in any way. I still suspect that this is an OS issue. I see myself getting at some point or another. If I had an urgent need for a new computer, I would probably still get the rMBP.
     
  14. blueicedj macrumors 6502

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    Jul 11, 2007
    #14
    Every game Nintendo makes is released at 60fps
     
  15. leenak macrumors 68020

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    Mar 10, 2011
    #15
    Well it is possible that something else is going on, who knows. Could be perception, could be something that is defective in some systems, could be some odd setting, etc. I just know my experience.
     
  16. Matrixfan, Jul 3, 2012
    Last edited: Jul 3, 2012

    Matrixfan macrumors member

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    Oct 10, 2008
    #16
    I was thinking about the same question. The resolution is not that much smaller than the rMBP's screen. IMHO it's all about optimization and integrity. I am amazed how well optimized iOS graphics acceleration is, and at the same time how poorly Apple implements GPU support on the desktop. AFAIK even the latest OpenGL is yet to be supported on the platform, let alone the speed penalty that comes from GPUs being designed with DirectX in mind. I really am a fan of the Mac platform, and willing to pay for good design, but graphics drivers on the Mac side are a complete joke compared to what feature set is available in Catalyst or Forceware. The concept of Core Image and Core Animation was so great back in the days, but it seems something is really missing, and my bet is the quality of the drivers. BD support is one thing that can be explained and understood from a business standpoint, but the state of GPU support on Mac OS X is a major drawback in 2012. LOL, I can't even tell the OS that my projector is not on and don't extend the desktop on it, and that's not even an advanced thing. Apple should be more aware of this and hire a bunch of engineers, tighten connections to GPU vendors, etc. With all this money they could even license DirectX from MS :p

    However there is one thing that is different on the iPad and the next gen MacBook Pro. The iPad is always running in a fixed mode that is similar to the "best for retina" setting. When any other resolutions are used on the MBP, non integer scaling has to be done. For example at the 1680 x 1050 setting the system renders at 3360 x 2100 and scales back to the native resolution, to 2880 x 1800. So this is a two step scaling method, and one is a non integer downscaling. I have read that apple uses different algorithms for the nvidia card and the HD4000 to achieve same quality on different hardware.
     
  17. Collin789 macrumors regular

    Collin789

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    Mar 29, 2011
    Location:
    Greensboro, NC
    #17
    I think it has to be a software issue. Explain why Mission Control and Launchpad don't lag. Iv'e heard of people saying its laggy but its never been laggy at all for me. However, web browsing is pretty bad.
     
  18. iamrobk macrumors member

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    Jun 30, 2012
    #18
    Well, the iPad has about 3m pixels, the rMBP about 5m. So it is a pretty big difference.
     
  19. Sambo110 macrumors 68000

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    Mar 12, 2007
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    Australia
    #19
    The rMPB absolutely destroys it hardware-wise too.
     
  20. iamrobk macrumors member

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    Jun 30, 2012
    #20
    Definitely. Just pointing out that the resolutions aren't really that similar.
     
  21. Matrixfan, Jul 3, 2012
    Last edited: Jul 3, 2012

    Matrixfan macrumors member

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    Oct 10, 2008
    #21
    Well yes, it has fewer pixels. I should have said same ballpark, and that is definitely true if we take processing power into account. Okay, this is a high level vs low level thing, but IMHO it doesn't change my point.

    It's like shooting in the dark, but maybe some web related rendering is responsible for slowing down. Like CSS, flash banners, etc. to tell the truth when I tried the rMBP at a store with a quite complex site it wasn't that bad, but that was after software updates.
     

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