After the initial assessment is complete the background and security checks start. It can take anywhere from a couple of months to well over a year to complete these checks.
Background check - verification of your claims, education and experience credentials done by visa post processing your application with cooperation of visa posts in countries your credentials were earned.
Security check is conducted completely outside of Immigration by Canadian security and intelligence agencies, with or without cooperation of proper authorities in countries where check is being conducted. It is looking deep into your life, background, activities, associations etc. to find out if you are or ever were involved or are or have been associated with someone who is or was involved in espionage, terrorism, radical movements, crimes against humanity, organized crime, etc.
Unfortunately authorities in some countries take months or longer than a year to reply to inquiries from Canadian authorities and in some countries check has to be done using old fashion spy methods. It all takes time and depending from your background, nationality, countries you lived in, people you associated with (knowingly or not), your activities etc. it may take anywhere from several months to well over a year to conclude
