Hi
I'm getting massive DPC latency spikes causing audio issues and jerky mouse movements on the host, whenever there is high CPU usage on the guest.
Host is Win 8 64bit, on a DX58SO with an i7 950 and 6GB RAM, VTx enabled, and VMs running on a 2x500GB RAID 0 partition.
Virtualbox version 4.3 r89960
Guests are Windows 7 64bit, 32bit, Centos 64 bit, all running latest guest additions, using 2 cores with 90% cpu limit, 2GB RAM. I haven't run any of these simultaneously.
Using DPC Latency checker 1.3 (which is apparently inaccurate in Windows 8) I get 500us - 1000us with host and guest idle. Running a 7zip benchmark causes spikes up to 280000us...
Let me know if you need more info?
edit: just tested with 32bit Win 7 guest, with single core and VT-x disabled and had no spikes