My Dad is a Naturalized Canadian (1976). I was born in 1980. Submitted data page of his passport, citizenship certificate, social security as well as my birth certificate, Nigerian passport data page and other documents necessary.I have a friend who submitted thru the embassy last year and he was 38yrs and he received citizenship certificate that same last year.
Like you said maybe the delay is because i submitted from with Canada. But they are not accepting documents except i can include medical records. I was born in LUTH and i am sure my medical record from 38 years ago surely would not exist or would be missing (poor record keeping in such institutions).