XP Performance in Hyper-V
I’ve found that Windows XP with more than 1GB of memory and multiple processors has some pretty terrible performance issues. I’ve also noticed that XP images that have been converted from a physical machine are even worst. There are many things to check for (Physical processor version on the host, make sure you have a single core and run the image with 512 or 1024MB of memory etc)
Another performance tip is to configure the ACPI Multiprocessor PC HAL to a ACPI Uniprocessor PC HAL: When using P2V migration images that had multi-core physical processors. In my experience Hyper-V integrated components says it is changing the HAL type, but does not.
You can download Microsoft’s DevCon command line utility to change the ACPI type without re-installing the Operating System. http://support.microsoft.com/kb/311272
The commands I used were:
devcon sethwid @ROOT\ACPI_HAL000 := +acpiapic_up !acpiapic_mp
devcon update c:\windows\inf\hal.inf acpiapic_up
Hope this helps and happy physical to virtualization migrations with XP.