The Cisco Umbrella roaming client has a virtually nonexistent footprint on a computer in terms of system resources, both for Windows and OS X. This is because the Umbrella roaming client does not cache DNS in any way, or expand in size or footprint over the course of time. DNS by design uses very little resources. This is also true of the Umbrella roaming client and the Umbrella service. The vast majority of computational power is held within our cloud, not on the local machine.
The Umbrella roaming client, even if doing hundreds or thousands of DNS lookups per minute, should not fluctuate beyond what is described below. If you see the Umbrella roaming client's resource usage exceed the general outline of the parameters here and it's causing issues, please open a support ticket.
Memory (RAM) & CPU (Processor)
The memory footprint of the Umbrella roaming client is consistently between 20-25MB in Windows, and 6-7MB in Mac OS X. Typically between %0 and %2 of CPU utilization is shown in the Task Manager (Windows) / Activity Monitor (OS X)
Storage (Hard Drive space)
The storage footprint is about 7MB of disk space for both Windows and OS X, with the possibility of up to an additional 10MB of logs being stored at any one time.