SAME PROBLEM - When parallels is running, wifi speed obliterated on mac mini 2012.
Running Mac Mini 2012 i7 10.9.4 16GB RAM, latest Parallels with Windows 8.1 VM. When the VM is running, my download speed on Mac side drops from 16 Mbps to < 1 or mostly, it barely functions at all! When I suspend or pause the VM, the download speed on Mac is restored to 16 Mbps! The download speeds inside the VM are abysmal, of course.
Strangely, disconnecting the Networking in the Parallels configuration does nothing to alleviate the problem. Simply having my VM running will seriously slow to nothing, my internet connection on the Mac side (and the VM connectivity as well). Also, lowering the number of cores dedicated to the VM (down to 2, out of 8) does nothing to help.
I've had to run a Cat5 cable for months in order to use internet because that seems to be the only workaround to this issue.
Truly awful. May be time to ditch Parallels because this problem seems ongoing and totally unrecognized by Parallels.
Last edited: Jul 29, 2014