Might go to New Delhi by mistake but they will transfer to London. All Afgs must fianlize in London.
There is no wait for Afgs that is different than others at CIC in Canada. Only when it goes to LVO then based on history of applicant one step can be added that is comprehensive security. Of course the Afg paperwork is also a mess and not everything is clear. For example mother's name is not on son's birth documents. Genius - right? So one has to explain to Visa officers why that is and they will ask more documents which will delay.
Anyhow, be patient.