Nope

Like D said, it doesn't really matter at lower speeds. A rigid bike will teach you better technique in getting over objects, how to adjust your weight for difficult climbs/descents, etc because suspension (though undoubtedly advantageous in many kinds of riding) can act as a crutch that keeps you from learning the proper ways to handle different scenarios you'll encounter when riding. When you get to a point where you feel like you've taken everything from your rigid that you can & its rigidness is only holding you back, that's when it's time to look into suspension.