ef37a wrote:So, do you mean disabling the network interface in Device Manager or just unplugging an Ethernet cable or on a laptop switching off the wi fi with the "aerial" button? Or/and turning off the router in the "staircase" bottom right?
In short, how deep do you have to go such that Windows no longer "cares"?
In short, airplane mode is just fine if you only operate a wireless interfaces, the 100% safe way is to disable the device, but also just unplugging the cable will work just fine in practically all cases.
To understand why - from the connection checking point of view, if you want to the absolute fastest you need to disable the network interface, as in that way the kernel will simply not enumerate it - it basically won't exist from the kernel point of view.
However, checking airplane mode is also handled at kernel level, so while technically it's a few more calls (instead of returning immediately, the kernel will enumerate the devices, and finding that the one device is wireless, check airplane mode and return right away), each of them takes next to nothing and in practice it won't make any difference. In the end it's checking a true/false value and that's what computers do best
If you have a wired connection, airplane mode doesn't help (it's only for the radios). In that case, if you simply unplug the Ethernet cable, control will pass from the client process to kernel to the interface driver. The driver will simply check if there's any active connection and return immediately if not, but of course one cannot be certain
that an hyper-sloppy programmer has put some useless time-wasting code in the driver... but it's very, very unlikely. So really no big deal - just a little more overhead but not so much. The only caveat there is that power management needs to be disabled - that's because the way it's implemented by the driver can be pretty intrusive
However, what takes steals processing power from real-time tasks is not the network checking itself - whatever way.. rather, it's the reconstruction and processing of any network-related information, either synchronously by your application or asynchronously by others.. say your mail client waking up deciding to check for mails, or a TCP server running in the background that suddenly starts receiving data, and has to spawn a handler thread which then start consuming the data, interpreting it and doing something in reaction...