That is 100% not true. Have you actually tried it yourself? The only Hypervisor that I have never had any timing issues on guest OSs is Hyper-V.
 
There were some problems in the HV-Versoin 1 days, but V2 and up, no problems any guest OS.
 
If you are using linux on Hyper-V, you should not use kernels older then 3.5. This is whan Microsoft started commiting all the HV-* modules directly to the kernel repos.
 
--Dave

From: Stanislav Sinyagin [mailto:ssinyagin@yahoo.com]
To: FreeSWITCH Users Help [mailto:freeswitch-users@lists.freeswitch.org]
Sent: Tue, 27 Aug 2013 08:16:07 -0700
Subject: Re: [Freeswitch-users] freeswitch on ubuntu VM on hyper-v

You will likely have audio distortions. OpenVZ or Xen virtualization should do a better job (myself, I run two production servers under XEN and never had problems with audio quality).

Search in Google for FreeSWITCH or Asterisk under Hyper-V, and you will see the whole spectrum of opinions, and no real detailed test results.




From: lloyd thomas <lloydie.t@gmail.com>
To: freeswitch-users <FreeSWITCH-users@lists.freeswitch.org>
Sent: Tuesday, August 27, 2013 3:10 PM
Subject: [Freeswitch-users] freeswitch on ubuntu VM on hyper-v

I just need a little advice setting up a freeswitch VM box shared with a http VM on hyper-v host and was wondering whether there are any gotcha's that I should be aware of.


I expect about 50 devices to be registered on it at any time and not expecting a high volume of calls.
It will be a fairly low spec dual core machine (dell sc1425), with 8gb ram

Thanks in advance for any advice.