Why causes Chrome to make my Mac unresponsive? 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.
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="&lt;some_path&gt;"),
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/.