n(CPU) > 1 => performance degrades on ubuntu

hi,

i'm running Parallels6 (Build 6.0.11992) on a MacBookPro i7 8GB.

VM is an Ubuntu

Code:

$ lsb_release -a              
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 10.04.2 LTS
Release:        10.04
Codename:       lucid

When i assign more than 1 CPU to the VM, Ubuntu feels sluggish.
e.g. I connect to the VM via SSH over the hostexclusive-network:
- After a while the echo "lags", when a key is pressed, you can watch how the input stops sometimes, when holding down a key
- Kernel dmesg

Code:

[    5.059988] CPU0 attaching NULL sched-domain.
[    5.059993] CPU1 attaching NULL sched-domain.
[    5.059994] CPU2 attaching NULL sched-domain.
[    5.059996] CPU3 attaching NULL sched-domain.
[    5.084995] CPU0 attaching sched-domain:
[    5.084999]  domain 0: span 0-3 level MC
[    5.085002]   groups: 0 1 2 3
[    5.085007] CPU1 attaching sched-domain:
[    5.085009]  domain 0: span 0-3 level MC
[    5.085010]   groups: 1 2 3 0
[    5.085014] CPU2 attaching sched-domain:
[    5.085019]  domain 0: span 0-3 level MC
[    5.085021]   groups: 2 3 0 1
[    5.085024] CPU3 attaching sched-domain:
[    5.085025]  domain 0: span 0-3 level MC
[    5.085026]   groups: 3 0 1 2
[   13.784933] eth2: no IPv6 routers present
[   27.595664] Clocksource tsc unstable (delta = 68643740 ns)
[   27.596265] Switching to clocksource acpi_pm

This doesn't happen with one CPU.

Has anyone experienced something similar?

Thanx

boecko