Performance Exchange 5.5 / NT4 Server

[Steffen Meier]

Hi,

I have ESX 2.5 running a NT4-VM with Exchange 5.5.

But for one VM I have a CPU-load >95 for 2-3 hours in the morning
It's an Exchange 5.5 running on that VM and the Exchange-Directoryservice
and Informationstore are consuming the CPU time.

I've double the assigned memory from 2 GB to 4 GB (maximum unter NT4) and
I've increased the CPU-shares for that VM from 1000 to 8000

But I see no difference - still the VM (Exchange) exceeds 95% CPU
utilisation for hours.
Users are complaining about slow response times....

I wonder where else I could try to fix this ?
The VM is running on a IBM x445 host with 16GB and 4 physical-CPUs together
with 10 other VMs.
The IBM-host CPU-load is about 75% and should have enough power to server
the Exchange-VM ?

thank you