Before you analyze in depth the runtime performance of your code, have the method millisecondsToRun: display how long it takes to run the code. To do this, add millisecondsToRun: to a method shown in a browser and have the system print the elapsed time to the Transcript. The expressions you add to the method are as follows:
Transcript show: ( Time millisecondsToRun: [ <code>. ]) printString; cr.
When you run the code, the time it takes to run the code prints to the Transcript.
Or, if you can run the code from a Transcript, Workspace, or description pane: