- Async validation will only be called on field blur now if sync validation passes and either the form is dirty or the form was never initialized. Discussion on #614.
This assumes that if you initialize your form with data, that data would pass async validation, so when the user tabs around between fields, async validation will not be initiated. However, if you have not initialized your form, async validation will fire on blur, even if no fields have changed.
Also: async validation will always be called before submission, regardless of whether or not the form is dirty or was initialized.