XorMon NG is able to monitor CPU and Memory usage of monitored SAN switches.
You can find CPU/Memory graphs under SAN total menu (all switches in single graph) and even under each switch.

Supported devices

• Broadcom Brocade and all its re-brands
• Cisco MDS

Why do not you have data in CPU and Memory graphs?

• Brocade: you might have very old switch firmware
• Brocade: It is not presented for Virtual Switches, just for default switch (usually VF:128)

Cisco MDS note: SNMP provides real time values for CPU/Memory usage only, not 5 minutes average which we would need.
Therefore you do not see in a graph 5 mins everage rather a few sec average from each 5 minutes. However it is still better than nothing.