>>>Looks like this might be known behaviour. See: https://stackoverflow.com/questions/31736496/why-does-adding-additional-angularjs-validation-directives-cause-asyncvalidator
>>>and https://github.com/angular/angular.js/issues/14691
>>>
>>>As suggested earlier there may be some condition that you can check in your directive to determine whether the asyncValidator actually needs to run. If it does not then you could just short-circuit the http call
>>
>>Do you know what condition that may be? In the meantime I also asked on StackOverflow (I didn't see your message until now)
>>
>>https://stackoverflow.com/questions/46101820/do-asyncvalidators-fire-all-the-time
>
>Just guessing (since I don't know the situation) but e.g. if the control value is empty or not dirty ?
>
>Actually I'm trying to forget all I know about directives and scopes since moving to Angular2 :-}

This doesn't seem to work

 if (!viewValue || element[0].$pristine) {
                        return services.Q.when(true);
                    }
                    
                    $log.debug("Firing server-side validations...");

e.g. I'm trying to only fire validators if I changed the element, but the $pristine shows undefined.