This is a serious & time-consuming stage(depending on which country are you coming from/residing) , involving many agencies, including CSIS, Interpol, NASC, Database Checking & touch-base with Local Police. Many things are considered here... the No. of countries visited, Applicant coming from 'certain' countries, ex-Servicemen [including Law Enforcement services], Prolonged stay in a country w/out sufficient docs to prove cause, frequent traveling to certain nations, your *Name (?), Inter-Religion/Nationality Marriages etc."
Some of you might know that people from Middle East take more time in issuing PPR, compared to people from USA, UK etc. It is because of intense Security check.
Hope you will find this helpful.