Memory leak
Probably you've already fixed it, but the applet is leaking RAM:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1997 user 20 481.5m 242.2m 23.4m S 11.8 1.5 434:16.74 panel-23-cpufre
RSS: 242MB is quite extraordinary after 7 days 10 hours of uptime/runtime.
After restarting:
397503 user 20 186.7m 26.8m 19.9m S 0.2 0:00.20 panel-23-cpufre