http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/time.htm 

[LV] Has anyone written a ''time'' chooser similar to the date chooser
widgets written elsewhere on the Wiki?

You can measure the runtime of a lengthy script with the following pattern:

----
[Tcl syntax help]
- [Arts and crafts of Tcl-Tk programming]
- [Category Command]