I am running a Windows 7 x64 guest on a 2012 15" RMBP. Often, my audio becomes delayed by around 300ms. (Sometimes, 200, other times, it's gone as high as 350ms.) I'm trying to play rhythm games so this is completely unacceptable. When I go into the audio device properties in Windows and change the samplerate, the problem temporarily goes away. (I've been switching back & forth between 44.1khz and 48khz as a really awkward workaround.) I found that the problem returns EXACTLY when the Mac OSX power save mode kicks in and disables the audio device. This means I can provide you with exact replication steps: 1. Be using some recent Mac laptop which has this power save function. 2. Start the guest and play some audio. Observe no lag. 3. Stop playing it. Turn your speakers up. Wait for a quiet "pop" sound to be heard, signifying that power save has gone into effect. 4. Play some more audio. 5. Observe that it's now lagged.