Virutalbox and SCO openserver 5.0.4 that disk performance has trouble.

Those day I trace problem, the user report typing and get stuck situation ... that's like system hang.
I try to read system usage from command ps, it's look like someone read database to take more cpu power ( 50 ~ 70% ), but in real machine that doesn't have this issue.
anyway, report user still keep eye on this situation and wait I provide solution ... QQ

* i5 3470, B75 chipset, 8G RAM, Intel 60G SSD. centos 6.3, virtualbox 4.2.12
   virtual machine, OSR 5.0.4, 1G RAM
* Realmachine, p2 400Mhz, 512M RAM 9G SCSI, SCO openserver 5.0.4
* script : ps -A -o "pcpu=" -o "tty=" -o "pid=" | awk '$1 > 10 && $3 > 500 {print  $1 " " $2 " " $3}
* who -ux # check which ip and login name.