When I am watching a YouTube video, the video will pause and freeze for about one second, every 10 seconds on the dot. I've timed it. I have also tried watching activity monitor but it doesn't show anything out of the ordinary spiking. And it's not Flash or the browser in particular, though they show the worst effect. But even as I type this, every 10 seconds it freezes. In other programs too I'm pretty sure I have seen this freeze. (lately I haven't used many other programs, to be honest, so I'm not 100% sure)

I am trying to avoid the brute force approach of removing things one by one and seeing if it stops. Before I resort to that, is there anything sort of like activity monitor but maybe that will graph usage so I can just look at a spike in usage from a single process? Or is there some other method you can recommend for finding out what is causing this every-10-second freeze?

This, by the way, is a few-month-old 17" MacBook Pro with a 2.8ghz i7 and 4gb of RAM and all updates.

2 Answers 2


Sometimes a good place to look is the syslog. If you know it's every 10 seconds then there's a chance that a message will get logged for whatever is happening. Try this in terminal and append the results to your question or even have a look yourself for anything that looks unusual which is happening on 10 second intervals.

tail -n 20 /var/log/system.log

You need to be an admin user to run the above command

  • Nope, nothing unusual in there.
    – Ricket
    Commented Feb 3, 2011 at 23:30
  • OK, can you elaborate on the effect you see. Does everything stop? So if you're typing, do the letters stop printing as if you're not hitting the keys and then catch up? Does the mouse pointer freeze in place? Commented Feb 3, 2011 at 23:37
  • Yes the letters stop printing and then catch up about 1.5 seconds later. The youtube video stops (but the audio keeps playing) and then, 1.5 seconds later, jumps to the frame it's supposed to be on and continues smoothly from there. The mouse cursor does not freeze, but if I click during that 1.5 seconds I can get it to very briefly show the spinning color pinwheel thing. Also Activity Monitor was smooth, so maybe it is just limited to firefox or flash.
    – Ricket
    Commented Feb 3, 2011 at 23:39
  • You could try a reinstall of Firefox. Have you got any addons/extensions installed? Sometimes they can be buggy and chew up memory on you which can have weird results. I'd suggest removing all extensions/addons via firefox prefs and then deleting it, emptying the trash and reinstalling a fresh copy and see how that goes Commented Feb 3, 2011 at 23:44
  • I'd also try using Chrome/Safari and YouTube. If you don't get problems with them when FireFox is closed at least you've isolated the problem to Firefox rather than Flash. Commented Feb 3, 2011 at 23:46

I gave it a while after posting this question but couldn't find a solution. I uninstalled what I thought was the most likely culprit: Little Snitch. Unfortunately the uninstall required a restart, so I don't know which one fixed the problem (or if it's really fixed) but after restarting, of course, the symptoms are gone. I'm honestly hoping it will happen again so that I can confidently reinstall Little Snitch, because I highly doubt it's the cause of the problem.

I think I've still noticed the problem but not quite as severe. It's quite possible that I haven't yet been running Firefox long enough, and it's something that happens over time (or at an untimely sleep which Firefox doesn't properly handle, maybe?).

Also, next time I notice this severe problem, I found some commands to use to try and monitor firefox: rwsnoop and iosnoop. They are command line tools which monitor application disk activity. If the every-10-second thing accesses the disk then I'll see it and that might help in debugging it.


It ended up being Firefox, and I've now been happily using Chrome for months with no Flash problems. Besides this freeze problem (which only showed up after several days of using Firefox, if I remember correctly), Firefox also uses a TON of memory, which is completely unacceptable. So those factors, combined with the fact that I received a Cr-48 shortly after asking this question (thus it runs Chrome and I want to sync with my laptop) means I am now a Google Chrome fan.

Also I really don't think it was Little Snitch. I did reactivate it sometime later after asking my question, and a month or two later I thought about how Little Snitch was just sort of allowing everything, and disabled it - but after switching to Chrome I didn't see these freezes again.

  • If you've tested multiple browsers, then I would consider (if you haven't already), foregoing Flash and using HTML5 on Youtube to see if it reoccurs. Otherwise, try another website like Vimeo and see if there's consistency in the problem. Commented Jun 6, 2011 at 1:02
  • There was consistency, it was with anything Flash in Firefox after Firefox had been running for a while. Thanks for reminding me of this question, so please check out my update to this answer if you're interested.
    – Ricket
    Commented Jun 6, 2011 at 5:16
  • Well, if HTML5 worked properly, and Flash consistently had issue, I'd manually remove the Flash plugin files (/Library/Internet Plug-Ins/), reinstall Adobe Flash, and test further. You mention Firefox, so again, I'm assuming you've tested other browsers. If it's only inside of one, then it changes the support path significantly. Commented Jun 6, 2011 at 5:25

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