So I guess that your wife is from an exempt visa country and that she can come in Canada and extend her visa easy. Where she is from ? It's not the majority of applicants in Singapore that is in this situation. In this case, I think that the only problem that you can meet is if she need to meet the agent for an interview.
I think that you will have the same time of treatment whatever where it's done. I don't know now, but before people did Outland application cause it was faster than inland.
I am little bit jealous that you can enjoy the time with your wife while the waiting Ahahah !
No seriously, I wish the best and a fast treatment of your application.