There is some variation between devices, however, there will be a 1.3MB~5MB increase in memory consumption, and a 2~10% increase in CPU utilization. Please check the details in the implementation manual under "Resource Consumtion" for more information.
When utilizing the Unity SDK, screen captures only occur for exceptions caught by Unity. For this reason, screen captures do not occur during normal operation, and regardless of the screen capture setting, CPU resources are not consumed.