[VB4.3] Win 8.1 x64 bad performance on Yosemite 20GB RAM

[luckylittle]

I need your help guys! I love Virtual Box, but for some reason my Windows 8.1 x64 Ent is running slowly, lagging and playing video is almost unusable and I don't know why. There are some OpenGL errors in the VB log, but I'm not sure if they are related.

Attached is my Vbox.log and here are the specs:
[*] Hypervisor: Virtual Box + Additions v4.3.22r98236
[*] Host: Yosemite 10.10.2 on iMac 27" (mid 2010), 20GB RAM, i7 2.93GHz, ATI Radeon HD 5750 1024MB (max res 2560x1440), 1TB HDD (21.79GB free)
[*] VM: 15360MB RAM, 8 CPUs out of 16 CPUs, Video memory 256MB (2D, 3D acceleration enabled), VDI file has 900GB (Use host I/O cache enabled)

Any help would be much appreciated!

[loukingjr]

Reduce the number of cores assigned to the guest to two.
Reduce the amount of RAM to the guest to 4GB.

I have no idea why you would create a 900GB .vdi on a 1TB drive.

[luckylittle]

I reduced RAM to 8GB and CPUs to 2. This made no difference. Videos are lagging and so is mouse sometimes.

See the screenshot from VM:
http://oi59.tinypic.com/2iafsif.jpg

Screenshots from the host:
http://oi60.tinypic.com/2dikfau.jpg
http://oi60.tinypic.com/24ux7wz.jpg

This is not a CPU/memory/HDD issue - they are all doing pretty much nothing. I had very similar setup (also large virtual disk) on OSX Mavericks and VMware Fusion and that was working fine.

[loukingjr]

Don't know what to tell you. I am running Win 8.1 64bit on the iMac in my signature and not only are videos not slow, I can watch NetFlix, YouTube and a movie in VLC simultaneously and my mouse does not lag, nor does anything else.

Perhaps someone who knows Windows more than myself has some ideas.

FWIW, My settings for Windows 8.1 64bit are 2 CPUs, 1.5 GB RAM, 256MB VRAM. 40GB .vdi

[artemissoftware]

Hi, I am running Windows 8.1 VM on a Mac Pro 6,1, 16gb, 3770 and was having real problems , guest screens went blank and Virtualbox CPU on Mac went to about 220% regularly for ages. I updated Virtualbox to 4.3.26, reduced CPU's to 2 and Memory to 4gb, install guest extensions and problem went away, running great now, performance similar to if I dual boot into native machine which I converted to VMDK using VMWare converter.