That's a simple question with a very complex answer. 

My experience so far is that Laserfiche doesn't seem to care one way or the other about whether the server it's on is virtual or physical, though most of the servers I work with are virtual. A server with X amount of memory and processor speed is going to function the same regardless of whether it's virtual or physical.

Assuming the physical box(es) hosting those VMs have sufficient resources and network bandwidth.

Where people seem to get into trouble is putting too many virtual machines with too many resources on the physical box running the virtual servers. The servers will start to fail if all of them are assigned almost as much memory and processor speed as the physical box hosting them, and put under too much load and all given equal priority.

That's down to the skill of the network admin.

What virtualization really maximizes is fault tolerance, deployment, and maintenance. It's a lot easier to restore a VM from a backed up image than to build a physical server from scratch.