Property binding executes when no one listens

This is not a bug per se, but if a property "foo" is bound to a script, the script gets executed whenever a variable inside the script changes. This is off course expected when someone listens to "foo". But if not, the script gets executed for nothing.

In the UI components team we're unsure how to deal with this fact, since we would like to avoid writing our components in a way that makes such code execute all the time, even for properties that gets rarely used. And the UI components will always contain a lot of API that normal applications never will make use of.

Is this a bug?
Should we provide functions in the API directly, rather than binding the function to a property? would that improve performance?