The Load client is a system load indicator, which displays a graph of the current and recent system load and/or a digital display of the current load.
The graphical display is a histogram drawn to an automatically adjusting scale. A "Scale" preference parameter (by default 1) sets the initial and smallest maximum of the graph. If the load exceeds the current maximum, the scale automatically doubles, and a red "tick" line is drawn to mark the old maximum. Thus, by default the tick lines represent loads of 1, 2, 4, 8, and so on (this is less cluttered than evenly spaced tick lines). When possible, the graph is scaled back up.
Clicking mouse button 1 on the Load button (by default) launches an xterm running "top" (so you can see what's causing the load).
The system load information is obtained from the /proc filesystem if possible, and otherwise from the "uptime" command. Load will work only if the output of the uptime command includes the current system load as the third from last field on the line (as is standard). (If you would prefer to obtain the load some other way, you need to change the procedure "GetLoad" in the file Load.tcl.)