Whether a scenario includes anonymous visitors or not, it is always best to minimize the number of visitors to whom the scenario applies, especially if you have a large number of site visitors. Consider the following example:

Here, the e-mail message you want to send applies only to visitors who are students. You estimate that almost all the people who are likely to respond to the mailing also belong to a profile group called Young, which you have set up for anyone under 35 years of age. Therefore, rather than having the scenario apply to anyone who logs in and visits the /Snowboards page, you can safely narrow its focus to people who belong to the profile group Young, thereby reducing the number of profiles that the Scenarios module must change as part of processing this scenario.

Bear in mind, however, that using profile groups to minimize the number of scenario participants does not always make a scenario perform more efficiently. Depending on their position in a scenario, profile group elements (“People in group X”) can behave as collective elements, and in this case they can have a negative effect on performance. See the next section, Minimizing the Number of Collective Elements, for more information.