Continuing to work with your menu system.
Examine commands which relate to CPU load statistics. Commands like sar, vmstat, etc. Research these commands and use them to create a file of running stats about your cpu load in cron (I can give you sudo to this if you need it). This should run say, once an hour to build a running examination of the system over time in a file. Now, add an item to your menu to parse the log from this command and draw a graph on the screen (using asc) of the demand loads over the 24 hour period preceeding. You may use any and all system commands to perform this. You decide which is best.