Have you set the right NFS tuning parameter using VSC2.0? Also have you set the Linux IO timeout values from the tools in VSC2.0? Also is the RH install NUMA aware. If it is then have you taken care to setup the memory appropriately - i.e. if the ESX host has 2 sockets and there is 8 GB of memory that has assigned 4GB local to each socket as per NUMA configuration. In the VM setup if you have chosen 6GB of memory, then it will pick 4GB from one NUMA node and 2GB from the other and thereby cause more overhead because the cache will keep switching between the two NUMA nodes.