OS X Annoying rhythmic lag in games

Discussion in 'Mac and PC Games' started by sammich, Feb 6, 2013.

  1. sammich macrumors 601


    Sep 26, 2006
    Initially, I thought this was a Steam related problem, since I've really only played CS:GO and HL2 recently (not including other, less intensive, non-3D games, they don't seem to exhibit this problem). Now having acquired Starcraft 2 (in prep for HotS) it also has the same problem.

    The basic problem is the FPS dips every few seconds or so, at roughly the same interval (hence, rhythmic). I'm on 10.8.2, on a Early 2011 15" MBP with the 6750M. When I didn't have this problem (somehow it went away for one miraculous session) CS:GO was perfect, no FPS dips, a good 60 FPS (no FPS counter, but close enough) on max everything, 1080p.

    In SC2, the lag presents itself everywhere, except in gameplay. In the rest areas (Battlecruiser, etc) this lag is in your face, especially when you watch any prerecorded video (like cutscenes and the news bulletins on the TVs). I play in windowed mode because I suspect it improves things, a little.

    One final piece of information: iStat menu is telling me I'm pulling 40-45W from the wall. Hell, sometimes my MBP uses that much just browsing the web (no flash). gfxcardstatus says the 6750M is being used. QuartzDebug doesn't seem to report anything useful. Also, I don't think it's solely an FPS issue since I think game time also dilates.

    So, you've managed to get this far into the post: what can I do? Could I boot into safe mode and see if it makes any difference?
  2. SingularityG, Feb 6, 2013
    Last edited: Feb 6, 2013

    SingularityG macrumors 6502


    Jun 7, 2012
    Since I updated to Mountain Lion, I get exactly what you describe in most games. It's more noticeable in more demanding games, even though just barely, really.

    On my 17" 2010 Macbook Pro, SC2 runs absolutely smoothly (Medium-High settings), but I do get the same issue with the vids.

    Some people suggested disabling Spotlight might help, but it didn't change anything in my experience.

    Another obvious solution would be to free up system resources by shutting down all background Apps. On the other hand, I do experience this under Bootcamp (just Windows&Games) in not so well ported games, like LA Noire, so it might be simply due to poor porting.

    Maybe it could be improved by HDD upgrade. All Macbook Pro base models are shipped with HDD with speed at just 5400rpm.

    Still, I think the root of the problem lies in Mountain Lion, which made many games utterly unplayable and the game developers [not doing/not able to do] anything about it. Maybe they wait for release of the next OS X update.

    Maybe we should get naive and for the time being, do the same.:)

    EDIT: Also, I forgot to mention that downloading and playing at the same time seems to worsen the issue.
  3. neokonig macrumors newbie

    Feb 6, 2013
    Re: Annoying rhythmic lag in games

    Starcraft 2 video stutter occurs for all machines (the stuttering in the Cantina TV or pre-campagin match videos) running new a newer OS. I have seen it on a couple different machines. I think this is either game related, or OSX version dependent.

    The other stuttering you are seeing may be related to v-sync issues or possible or automatic graphics switching/power management issues. Not sure if PRAM reset could help?
  4. edddeduck macrumors 68020


    Mar 26, 2004
    Sounds like you might be running at too high a resolution (or maybe texture settings), the pulse will usually occur when your graphics card is being starved of data and is waiting on the upload to the card.

    Their are other things like thread contention that I have seen cause the pulse but the first thing I would do is drop your settings and see if it goes away? If it does then start to turn things back on one by one, its likely a combination of high resolution with large textures of particle effects will be causing the pulse.

    I don't have the games in question but I have seen this pulse effect many times when optimising games over the last decade and usually it's the card being starved for some reason or other.

  5. Sondrix, Feb 18, 2013
    Last edited: Feb 18, 2013

    Sondrix macrumors newbie

    Nov 6, 2011
    I think I know the answer! It is overheating.

    This happened to me a couple weeks ago. I was playing counter strike: source and fps was fine for the first 5 minutes. Then fans rammed up to full speed and the fps would dip every 10 seconds making it unplayable. I suspect the CPU is throttling causing the dips.

    My solution is to raise it up on a laptop stand, use an external keyboard and have a nearby fan turned on. It's not ideal to do this every time but it's Summer and hot down here in Australia so can't complain.

    Have the fan directly facing the laptop so as to move hot air away, it does a great job of cooling the aluminium case too.
  6. SingularityG macrumors 6502


    Jun 7, 2012
    Yes, overheating can contribute to this, but so can many other factors.;)

    If you start noticing your fans running more often on a higher speed or louder, the easiest solution is to clean them of all accumulated dust.:)

    I usually do this once a month to keep the insides of my Mac nice and ventilated.
  7. sammich thread starter macrumors 601


    Sep 26, 2006
    Okay, I think I should update this thread on my 'solution'.

    The answer? Don't have an external monitor plugged in.

    It's definitely not a heat related issue, since as I said in my original post that my machine was barely breaking a sweat and it wasn't pulling much power from the wall.

    While I was troubleshooting, the thing I noticed was that CPU usage for the game process was very high. Basically pegged as many cores as it had threads on.

    When I play on the internal monitor only, it's gloriously smooth, CPU usage is low, around the 20-40% mark (for CS:GO, SC2). So something to do with the thing. I have no idea. It's annoying since I want to play on the larger screen, ext. KB and mouse. Oh well.
  8. edddeduck macrumors 68020


    Mar 26, 2004
    When you plug in an external monitor you are instantly halving the resources available to the game as the resources are split between the monitors.

    Have you tried running with the lid closed, so you only have one monitor active? That *might* help depending on how the game and OS is coded.

  9. sammich thread starter macrumors 601


    Sep 26, 2006
    I should've mentioned that: it's always in clamshell. Besides, I'm not totally sure if the 'resources' are split evenly, since the OS only tells the GPU to redraw the parts of the screen that are changing. The GPU RAM is split, yes, but RAM allocation doesn't impact performance unless you run out texture buffer.

    At least, that's the way I've understood it thus far. Still doesn't explain why the CPU usage for the game goes up several times though.
  10. benthewraith macrumors 68040


    May 27, 2006
    Miami, FL
    This only works if you're running the game in a lower resolution, and even then it would be smarter to run the game in a lower resolution full screen as opposed to having the graphics card draw both the OS and the game at the same time. The graphics cards in Macs have never been "fabulous" compared to some of their competitors' offerings.
  11. MagnusVonMagnum, May 28, 2013
    Last edited: May 28, 2013

    MagnusVonMagnum macrumors 601


    Jun 18, 2007
    I've noticed gaming on my Mac Mini often stutters every couple of minutes for a split second and then all is fine again. It doesn't seem to matter much what game it is from a SCUMM (Lucasfilm) game to running an old old game in XP under virtualization, they all seem to stutter sound or video momentarily.

    I'm going to try disconnecting my 2nd monitor (which isn't turned on most of the time anyway) and see what happens as someone suggested, but I've only ever seen this problem in Mountain Lion. I had two monitors connected all the time with my old upgraded PowerMac and even when playing 3D shooter games like No One Lives Forever 2 or Call of Duty on it, it NEVER stuttered. I would think a quad-core i7 running Call of Duty 2 wouldn't have any issues. I suspect there is something in the OS interrupting things somehow. It is very annoying to say the least. I can't help but wonder if the 4 cores has something to do with it also after reading of similar stutters on some games with Windows machines that have quad-cores instead of dual-cores (e.g. certain Telltale games stuttered until they told Windows through task control to allocate 4 CPUs instead of 2; there is no such thing in OSX that I know of).

    I do have my hard drives using RAID0 so I don't know if that could interfere somehow (normally I'd think having the drives run 2.5x faster would be a good thing, though).


    Disconnecting the 2nd monitor made no difference what-so-ever.

    I did find this MDS error in my logs (noting that it was running in Activity Manager): deny mach-lookup com.apple.ls.boxd

    Looking that up on Google, I found the following page: http://www.princeton.edu/~jcjb/docs/osx_error_fix/

    It suggests rebooting into Safe Mode to get rid of the problem. I'll try that next and see if it makes any difference.


    Safe Mode doesn't really load right with a RAID0 boot configuration. Still, the log errors went away for the moment at least anyway. I see no correlation to the stutters in Call of Duty 2. They seem to occur when the game loads new information off the hard drive (could be something with RAID0 even).
  12. Jethryn Freyman macrumors 68020

    Jethryn Freyman

    Aug 9, 2007
    Running in windowed mode can actually make games run worse, weirdly enough.

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