Hilmar,
ATC() is going to be faster because $ is case sensitive. To use $ you either have to upper() or lower() the whole memo before you can successfully look for the existence of the search text. Even if the memo was stored as UPPER() or LOWER() I doubt that there's significant difference between the two. $ is returning a boolean ATC() is returning an integer. They are both using the underlying C string functions to do the seek so they are equally fast.
>Do you think there would be an advantage in using at() instead of $, simply to check for the existence of a string?