ANSYS Workbench is a "computer hungry" application due to the complicated operations it's doing while working with a product. You will need processing power and graphical processing power to work fast with the items opened. Rendering is used by the CPU and that's why you will need a minimum of quad core CPU.
The minimum recommended specs are as follows:
- a 64bit capable CPU
- a Quad-core CPU with at least 3 GHz frequency
- 16/32 GB of latest DDR RAM
- RAID disks, but a HDDs with 10-15000 RPM are also recommended
- dedicated graphic card (excluded gaming graphic cards).