Do dynamic classes affect performance?

programming flash
1

From what I hear, getting/setting dynamic properties is a lot slower than regular properties.

But does allowing a class to be dynamic slow down the entire class for regular property getting/setting?

For instance, let’s say I have this class (pretend those properties have setters as well):

public dynamic class Hero
{
   public function get endurance():int
   { return _endurance; }

   public function get strength():int
   { return _strength; }

   public function hit(target:Enemy)
   { target.damage(this.strength); }
}

Since the class is dynamic, properties can be added on later, such as:
hero1[“magic”] = 500; or hero1.magic = 500;

Obviously, calling and setting the “magic” property will be a lot slower, but will all properties become slower to get/set just because the entire class is set to dynamic?

Is it better to not set the entire class to dynamic, and instead create a new dynamic object, “additionalStats” where properties can be get/set to instead?