VirtualBox 4.3.6 on FreeBSD 9-STABLE - Windows 7 Client: clock synchronization issues

[Maurizio Vairani]

Hello,

I am using VirtualBox 4.3.6 on a FreeBSD 9-STABLE r261225. The clock in 
Windows 7 client  is slow and I need to synchronize it every minute with 
the server with NetTime, an utility for time synchronization with SNTP.

While I am writing this mail the NetTime log is :
07/02/2014 16:16:12 Time Updated: +5,543s         Network became active
07/02/2014 16:17:20 Time Updated: +7,387s         Regular Update
07/02/2014 16:18:33 Time Updated: +13,03s         Regular Update
07/02/2014 16:19:46 Time Updated: +12,36s         Regular Update
07/02/2014 16:21:02 Time Updated: +15,33s         Regular Update
07/02/2014 16:22:13 Time Updated: +11,37s         Regular Update
07/02/2014 16:23:27 Time Updated: +13,2s          Regular Update
07/02/2014 16:24:42 Time Updated: +14,54s         Regular Update
07/02/2014 16:25:58 Time Updated: +15,75s         Regular Update
07/02/2014 16:27:08 Time Updated: +9,792s         Regular Update
07/02/2014 16:28:21 Time Updated: +12,62s         Regular Update
07/02/2014 16:29:34 Time Updated: +13,15s         Regular Update
07/02/2014 16:30:47 Time Updated: +12,32s         Regular Update
07/02/2014 16:31:59 Time Updated: +12,12s         Regular Update
07/02/2014 16:33:32 Time Updated: +31,79s         Regular Update
07/02/2014 16:34:51 Time Updated: +19,08s         Regular Update
07/02/2014 16:36:10 Time Updated: +18,49s         Regular Update
07/02/2014 16:37:25 Time Updated: +15,19s         Regular Update
07/02/2014 16:38:48 Time Updated: +22,48s         Regular Update
07/02/2014 16:40:05 Time Updated: +16,23s         Regular Update

Also the DPC latency of the Virtual Machine is to much high. I have used 
the DPCV Latency Checker V 1.3.0 (dpclat.exe) and it show values up to 
500000 microsec.

What can I do ?

Thanks
Maurizio