I know this is an old post but...

I have a scenario where setting processor affinity might make sense, please tell me it I am wrong. I am setting up a SQL Express on a virtual machine which means the I can only use 1 vCPU to run SQL. My virtual machine sole purpose is to run SQL for 10 users and I was thinking that if I gave the virtual machine 2 vCPUs and set SQL to use the second vCPU it would perform better than having a virtual machine with only one vCPU. My understanding is with virtual machines is that since all of its resources are virtual and the hyper-visor is diving up its resources to the VM that CPU Affinity and NUMA issues would not occur. Wouldn't it be better to have the OS using vCPU1 as its starting point and SQL Express run on the second vCPU? The machine that is currently fulfilling the role that this new VM is going to replace is about 10 years old running SQL 2005 Standard on a dual core processor that is also a Domain Controller and a file server and works without any issues. I await your advice.