Running any database in a Virtual machine (either VMware or Microsoft) will not perform well under load.
Virtual Machines use virtual disks for storage which adds an additional layer of processing which has to happen before the data can be written. In addition your memory and CPU are not all your own, so this can cause more slow down. Virtualization is great for Dev and QA database servers. I usually don’t recommend it for production database servers, especially ones that will be using a large amount of load.
This is a patently wrong answer. VMware VI3 runs Oracle and SQL Server just fine. In VI2, the virtual machine was limited to 2 procs and 3.6GBs of memory, and it VI3 the virtual machine can have up to 4 procs and 64GBs of memory and with the lastest release supports jumbo memory pages for cacheing in memory. I would suggest you go to www.vwware.com and search on Oracle and get up to date.