Peter,
Once in memory, procedures or functions tends to remain in memory. This has been the case with FoxBASE/FoxPro for at least 13 years. I this is the reason that the CLEAR PROGRAM call exists.
Second, in a compiled executable, this probably wouldn't occur. The tokenized code is all in one file (the executable or app file) so there's no search the path. This may be causing the delay you see.
George
Ubi caritas et amor, deus ibi est