How to efficiently match the namespace of an element in java?

The test() function below checks if the element matches a predefined namespace NSURI:

class MyClass {
    private static final String NSURI = "http://example.com/mynamespace";

    ...

    public test(Element e) {
        return NSURI.equals(e.getNamespaceURI());
    }
}

Is the string comparison efficient? I have to iterate many nodes, potentially having different namespaces. But, doing a string comparison each time seems wasteful.

Is there a faster way to do a namespace comparison?