Where I work, we are in need of upgrading our ClearCase servers and it's been proposed that we move them into a new (yet-to-be-deployed) VMmare system.
In the past I've not noticed a significant problem with performance with most applications when running in VMs, but given that ClearCase "speed" (i.e. dynamic-view response times) is so latency sensitive I am concerned that this will not be a good idea. 
VMWare has numerous white-papers detailing performance related issues based on network traffic patterns that re-inforces my hypothesis, but nothing particularly concrete for this particular use case that I can see.
What I can find are various forum posts online, but which are somewhat dated, e.g.:
  ClearCase clients are supported on
  VMWare, but not for performance
  issues. I would never put a production
  server on VM. It will work but will be
  slower. The more complex the slower it
  gets. accessing or building from a
  local snapshot view will be the
  fastest, building in a remote VM
  stored dynamic view using clearmake
  will be painful..... VMWare is best
  used for test environments
(via http://www.cmcrossroads.com/forums?func=view&catid=31&id=44094&limit=10&start=10)
and:
  VMware + ClearCase = works but
  SLUGGISH!!!!!! (windows)(not for
  production environment) My company
  tried to mandate that all new apps or
  app upgrades needed to be on/moved
  VMware instances. The VMware instance
  could not handle the demands of
  ClearCase. (come to find out that I
  was sharing a box with a database
  server)
  
  Will you know what else would be on
  that box besides ClearCase?
  
  Karl
  (via http://www.cmcrossroads.com/forums?func=view&id=44094&catid=31)
and:
  ... are still finding we can't get the
  performance using dynamic views to
  below 2.5 times that of a physical
  machine. Interestingly, speaking to a
  few people with much VMWare experience
  and indeed from running builds, we are
  finding that typically, VMWare doesn't
  take that much longer for most
  applications and about 10-20% longer
  has been quoted.
(via http://www.cmcrossroads.com/forums?func=view&catid=31&id=44094&limit=10&start=10)
Which brings me to the more direct question: Does anyone have any more recent experience with ClearCase servers on VMware (if not any specific, relevant performance advice)?