Bad load balancing of network traffic between processes I just switched from Linux to OS X by getting a MacBook Pro. A very annoying problem with OS X is that if I download something from e.g. my ISP's CDN, which can max out the connection, I will loose connectivity from all other applications.

On Linux if I was downloading a large file from a server that maxed out my line, I was still able to send e-mail and browse the web. It looks like on OS X a download hogs the connection so completely that DNS queries will fail while the download is going on, which prevents other applications from working properly.

Are there any kernel parameters or similar that can be tuned that will improve this behavior?
You can use pfctl to limit bandwidth (up or down independently) based on IP address.  Alternatively, you can use it to do some mild QoS so that DNS requests &amp; responses are given top priority, which I think should help much of your pain.