What does "Don't take too long." mean in English for Spanish?

In English for Spanish, "Don't take too long." means:

¡No tardes mucho!

Listen to "Don't take too long.": (If you have an HTML5 enabled browser, you can listen to the native audio below)

This is a phrase that is used in the GamesForLanguage English for Spanish Language Game in the following scenes:

• English for Spanish 3, Level 2, Scene 4