Virtualbox gets slower with more CPU cores

Vamp898 · 2014-01-09 00:43:30

There have been smiliar discussions but none solution yet so another try

Im running latest VBox on a fully updated arch and i have the following issue.

The more CPU Cores i add to my Virtual Machine, the slower it is.

The Machine is an Windows 7
Host CPU is an AMD FX 8150

If i use 1 CPU core, its amazingly fast, i can play 3D Games without problems and everything runs fine.
With 2 CPU Cores its only about the half speed and its already a bit laggy in some situations
With 8 Cores the Machine is unusable, bootup takes very long, sound laggs a lot and every application lags incredible.

There is also an addition to this strangeness

If i give the VM 8 Cores and run the Application using 1 of this 8 cores, its still veeeery slow, but much faster than when i tell the Application to use all 8 cores.

Does anyone knows why VirtualBox gets slower the more cores you use? Why do they even built in this function at all? Isnt it inteneded to speed things up?

If anyone has a clue how can i use all my cores in the Virtual Machine (with Direct3D Support, absolutly needed! so no KVM!), i would be very thankfull.

Last edited by Vamp898 (2014-01-12 03:26:45)

mandog · 2014-01-10 12:31:27

For starters if you use all 8 cores you are slowing the host down that is obvious I use a amd 6 core, in bios I can stipulate cores for virtualisation so I use 2 cores, Win7 runs at native speed in vbox on my machine.

Vamp898 · 2014-01-12 03:27:23

I understand what you say, but 8 Cores shouldnt be less than the half Speed of one core.

Beside this, all other Virtualisation Software (even Microsofts Hyper-V) can do this without any Problems.

Arch Linux

#1 2014-01-09 00:43:30

Virtualbox gets slower with more CPU cores

#2 2014-01-10 12:31:27

Re: Virtualbox gets slower with more CPU cores

#3 2014-01-12 03:27:23

Re: Virtualbox gets slower with more CPU cores

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