The requirements for the rendering service depend on the type of your Unblu installation.
Baseline Hardware Requirements for Single- or Multiple-Node Unblu Cluster Setup. Note that the resources required for the Rendering Service are listed as part of the entire system. See also Cluster Hardware Requirements Typical Setup.
The universal co-browsing capabilities that the rendering service provides are relatively expensive in terms of compute resources. This is because each universal co-browsing session launches an entire new browser on the server. The Rendering Service should therefore be considered separately when calculating the compute resources required.