Currently Being ModeratedNov 14, 2012 8:06 AM (in response to small dog)
There's no easy way to monitor bandwidth usage per process using built-in tools. This page has some suggestions for third-party software, which I can't vouch for:
Probably the demo of "Little Snitch" is the best option. I recommend you uninstall it once the question is answered.
Currently Being ModeratedNov 14, 2012 2:11 PM (in response to small dog)
I think I got it. I installed the Rubbernet, and it looks like most data is consumed by email application. Even after all messages appear the program continues downloading data at high rate. It swallowed 13MB in couple of minutes. This can easily explain my usage.
I wonder if there is a way to limit email downloads somehow.
Thanks for replies.
Currently Being ModeratedNov 14, 2012 3:46 PM (in response to small dog)
Another discovery: after closing email app by clicking the red dot it stays active and continues consuming data. So to prevent this you have to shut it down from the menu.
It also looks that Safary tends to consume more data than expected. Is it because of the high definition monitor? Is there a way to limit it besides reducing the screen resolution?
Currently Being ModeratedNov 16, 2013 7:56 AM (in response to small dog)
Safari will download larger images if websites use 'responsive' designs. There are many ways to do this, the idea being that high resolution screens get bigger images so that the 'jaggy compression' isn't as visible. If your screen width is large Safari will ask for the biggest files.
Sadly some ways to achieve this in HTML5 result in both the small & large image downloading. It obviously can waste data transfer.
I'd strongly suggest you disable tethering as much as possible especially if you haven't tried to disable all of the Air's background updates (App Store updates, individual app update checks etc). iTunes also will try to get podcast updates, Mail will try to download attachments… that is a lot to turn off.
OS X doesn't attempt to limit these tasks on cellular, so it's possible that they will simply run for hours over the slower cellular connection. Use a real wifi hotspot to limit the cellular usage from the Air.
The iPad is far better at 'knowing' when the network should be constrained because it is using cellular data, use that for email if possible.