Perfomance issue on one NFS filesytem within SAP server running with RHEL OS

One file system /usr/sapmnt is mounted within OS which is an NFS filesystem. This is an SAP server with CI & DB nodes, and these 2 nodes are in cluster. The /usr/sapmnt filesystem is mounted on both nodes via NFS. Further we are facing performance issue while accessing this file system and ls command get hanged when executed. Also this file system has more than 4 lakh of files within it. This is impacting the SAP application. Has anyone came around this situation and would like to know the probable cause.