I'm asking this mostly out of curiosity, as I've given up on finding a practical solution. Everyone knows that Chrome makes Macs sluggish, especially if you have a lot of tabs open. My question is what causes this, since it doesn't seem to be due to memory or CPU use.

I have a habit of keeping around 100 or more tabs open in Google Chrome, in several windows. If this number gets too high then my Mac starts to become unpredictably unresponsive - I'll sometimes have to wait a few seconds after clicking or typing for the input to be accepted, for example, or if I'm playing a game the frame rate might drop to 2-3 frames per second for a minute or two before recovering. This happens particularly if I have Keynote or Pages open in addition to Chrome. Using the Chrome plugin called "The Great Suspender" helps quite a bit, especially with keeping CPU use down, but it doesn't completely solve the unresponsiveness issue.

I used to think that this was a memory issue, but after buying a new Macbook with a lot more memory a year or two ago, this seems not to be the case. Activity Monitor tells me I currently have 4.6Gb free, and this issue can occur when less than half my 16Gb RAM is in use. It doesn't seem to be due to CPU use either (unless it's caused by sudden spikes), since I can keep that down to around 2% most of the time.

So if it's not memory or CPU that Chrome and other applications use up to make my computer behave this way, then what is it? And (since it can't hurt to ask) is there anything I can do to mitigate it?

Finally, I'm using Mountain Lion. Is this issue the same, better, or worse in Mavericks? Whether I will upgrade or not will be determined solely by this issue.

  • Chrome has a built-in taskmanager, could you check it?
    – Rob
    Commented Feb 12, 2014 at 8:46
  • @Robuust it doesn't report much I didn't know. I.e. there are around about 25 active processes, mostly taking about 50Mb of memory and less than 1% CPU each, plus loads of tabs with no associated process, because of The Great Suspender. The only slightly surprising thing is "GPU Process", taking 455Mb. Whether this is GPU memory or system memory it doesn't say, but if the former then perhaps GPU memory is the issue.
    – N. Virgo
    Commented Feb 12, 2014 at 9:01
  • 1
    I haven't done any testing but I'm going to go out on a limb here and say keeping 100+ tabs open in any browser is going to cause performance issues. Can you tell us why you're doing this? Commented Jul 13, 2014 at 10:52
  • @AlistairMcMillan I'm a busy scientist and have to keep track of a lot of things I'm part way through reading and will come back to later. Obviously having 100+ tabs isn't the best way to do this, but the only alternative is bookmarks, which doesn't really work for me either. (I find I just forget about them.) These days I use a plugin called "the great suspender" to free up the tabs' resources, which helps a lot. I'm pretty sure the problem is the graphics memory they consume.
    – N. Virgo
    Commented Jul 13, 2014 at 10:59
  • I understand what you mean about bookmarks within browsers, I tend to forget them too. Have you considered using a bookmarking service like Pinboard though? I find myself actually getting more use out of something like. Likely because it isn't tied to a particular device or even browser. I particularly like that I can tag something as "read later" at the moment I bookmark it to distinguish it from things I want to keep longterm. Commented Jul 13, 2014 at 14:30

1 Answer 1


This is the common problem which can be related to anything, like:

  • Chrome bugs,
  • network issues (check logs at chrome://net-internals/),
  • active extensions are slowing down web browser in general,
  • performance issues (either your machine is slow or you've too many tabs opened),
  • slow disk access, especially when your cache folder is huge with too many files.

    E.g. you may consider moving your profile folder into quick access drive.

Here are few suggestions:

  • restart web browser (also kill all chrome processes),
  • run in Incognito mode, to see if this could be related to some slow extensions,
  • create a new profile with no extensions and see if that helps,
  • install addons which aims limit the page processing (e.g. OneTab, ad blockers),
  • run Chrome in different user data dir (--user-data-dir="<some_path>"),
  • run with --disable-hang-monitor to suppress hang monitor dialog,

    Suppresses hang monitor dialogs in renderer processes. This may allow slow unload handlers on a page to prevent the tab from closing, but the Task Manager can be used to terminate the offending process in this case.peter.sh

  • make sure Chrome uses GPU process to enhance performance (see: chrome://gpu/),
  • generate network log file at chrome://net-internals/ and report the issue at bugs.chromium.org.

Debug suggestions:

  • check: chrome://flags/
  • check debug network log file generated by chrome://net-internals/
  • run chrome://tracing/
  • see other internal Chrome pages at chrome://chrome-urls/.

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