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.