ISSUE: Performance Tab grayed out in Spectrum for Cisco ASA 55xx series devices
ROOT CAUSE: Devices are not officially supported so they model as GnSNMPDev. GnSNMPDev models only support mib-2 standard.
RESOLUTION: Use the Device Certification tool to set sysObjectID 18.104.22.168.22.214.171.124.1902 to use the GnCiscoDev model type. Destroy and recreate any existing Cisco ASA 55xx devices modeled using GnSNMPDev so they remodel using GnCiscoDev.
Reference the "Certification User Guide" for more information on using Device Certification.