there is not any difference between QSW and FSW regarding Medical and Security check,both of them are going on in the same way regarding these 2 things,the difference is in eligibility,
QSW applicants are selected by Quebec(different rules for Quebec ,Quebec has the right to choose and select its candidates then federal part gives the visa after security check and medical,so once they have CSQ ,it means they passed eligibility.
FSW depends on different criteries completely(expierence,education,fees,age,priority for occupations....)
so when every program pass eligibility ,it is going in the same steps(Medical and security check),but the question is still,if security before medical or after it,for us QSW we concluded that security check started now before medical and when they finish security check,then they send our medicals becuase we have passed eligibility when we got CSQ,later they will send the visa within 2 months maximum after medical,but for FSW as i noticed from the first email of our friends wishfullman,so i can predict that his seucrity check started after medical,when his security check finish,once they send the visa .
The nationality does not play any role in security check,i know some people r from syria and Iraq,their security check took just 3 months,and at the same time know some applicants from Lebanon,they lived just in one country and their security check took about 8 months and sometimes 10 months,this is like a dark room and no one can know what they r doing and which criteries they use to do this important step for everyone.
Note: maybe they speed up security check for FSW coz they set up a new program for next year and they feel they have to finish these files very quickly.
regards