IWSVA can be installed on hypervisors (VMWare ESXi or Microsoft Hyper-V). If another virtual machine has already allocated some OS resources in the hypervisor, IWSVA will not perform as expected. As a result, the users will experience a slowdown in browsing even if there is still an acceptable concurrent connection amount of resources in IWSVA.
To avoid this issue, CPU and Memory reservation must be checked.
For detailed information refer to the following topics in the InterScan Web Security Virtual Appliance 6.5 Service Pack 2 Installation Guide: "Creating a New Virtual machine" and "Creating a New Virtual Machine Under Microsoft Hyper-V for IWSVA" .