Java, invoking constructor by reflection

How many times is slover to invoke constructor by reflection eg.:

Class c = map.get("somestr");
Constructor t = c.getDeclaredConstructor(int.class,MyClass.class);
MyObject o = (MyObject)t.invoke(<params>);
or
Constructor t = map.get("somestr");
MyObject o = (MyObject)t.invoke(<params>);

than using the keyword new?

Assuming the class will be cached.