It really depends on what you're doing on the switch. Notable CPU load is expected when running some command outputs like show tech or even some debug commands. You can check the output of the top command to see what processes are consuming the largest amount of CPU resources. You can also run the show cpu-monitoring to see CPU utilization from the last 1 hour.
When some processes like bcmRX, bcmTX are using up your processing resources, it could point to packets being forwarded via the CPU as opposed to being forwarded through the ASICs. You can check this by observing your L2Stats and IPStats. Just make sure you've cleared the counters before starting your observation window.
