linux - ubuntu 12.04 system running so slow after installing xen and changing grub settings -

linux - ubuntu 12.04 system running so slow after installing xen and changing grub settings -

i have ubuntu 12.04 scheme installed xen using these instructions: https://help.ubuntu.com/community/xenproposed

i set memory limit 512m. now.. when reboot computer, slow, it's taken 10 minutes render default desktop (kate) after log in. i'm not savvy plenty linux know how undo properly. if wanted test undoing changes grub, reverse of command?

sudo sed -i 's/grub_default=.*\+/grub_default="xen 4.1-amd64"/' /etc/default/grub

if have other suggestions on how can resolve this, that'd great. thanks.

i had set next value in /etc/default/grub:

grub_default=0

linux ubuntu-12.04 xen