virtualbox.org

Hi,

Try disabling the USB support (remember to uninstall the VBOX additions and then install them from zero or you'll get hardening errors). SinceI disabled them, the VM now is much more responsive. Give it a try

Just thought i'd confirm some of the findings here. Running a windows 10 vm on OSX VirtualBox 4.0.14 on a Core i7 4 physically cored machine (8 with hyperthreading). I used to run this VM windows 7, which worked perfectly fine set to 4 cores. After windows 10 upgrade, anything higher than 2 cores and all audio starts to stutter and performance is generally bad.

I have read that it can be a scheduling issue in that the hyper visor need to make sure all required cores are free for execution before it can hand of processing to the virtual machine (this was in regards to microsoft's hyper-v thou, but likely applicable). But why the reduction in performance on windows 10?

elupus wrote:on a Core i7 4 physically cored machine (8 with hyperthreading)

Uh... a 4 core machine, with hyperthreading, has... 4 cores. Core means independant silicon, basically a complete processor.

You mean that hyperthreading gives you 8 vCPUs, not 8 cores. Digging deeper, what it really means is two pipelines per core. Like having two heads on one body.

elupus wrote:Just thought i'd confirm some of the findings here. Running a windows 10 vm on OSX VirtualBox 4.0.14 on a Core i7 4 physically cored machine (8 with hyperthreading). I used to run this VM windows 7, which worked perfectly fine set to 4 cores. After windows 10 upgrade, anything higher than 2 cores and all audio starts to stutter and performance is generally bad.

I have read that it can be a scheduling issue in that the hyper visor need to make sure all required cores are free for execution before it can hand of processing to the virtual machine (this was in regards to microsoft's hyper-v thou, but likely applicable). But why the reduction in performance on windows 10?

I can confirm that I had exactly the same situation. I am running VirtualBox 5.0.16 on Windows 10 64bits host and with a Windows 10 32bits guest (both W10 version 1511-10586.164) on a Core i7 4 physically cored machine (8 with hyperthreading). I originally assigned 4 CPUs to this machine and had distorted sound and heavy cpu load on the host machine. Playing a Youtube movie in the guest was almost impossible. Reducing the number of CPUs to 2 and the sound is okay and Youtube movie plays smoothly.