It can take 3-4 years but that is extreme. In most cases it takes less time than that. However, you will have to answer the questions newtone mentioned. If you married someone you knew for a very short time, immigration may believe it was a fake marriage set up with the purpose of you gaining PR. If they think that, it is your problem to prove them wrong and unless you can prove them wrong, there is no PR for you. You need to mail them with your application all proof you have of your relationship being genuine, how you met, how you fell in love, emails you wrote to each other, phone bills showing you phone each other, pictures of you together, proof of trips you have taken together, your joint lease, utilities, bank accounts and your life insurance policies listing each other as beneficiary or at least some of the above. If they think your story is fishy, they can call you for an interview which will delay your application. If you pass the interview, you will get your PR. If you fail, if you apply outland, you can appeal, inland you would have to apply again from scratch.
The processing time if all goes smooth also depends on if you apply inland or outland. If you apply inland, it is 10-11 months for your first stage approval which upon you could get an open work permit and another 9 months for PR. If you apply outland, it is 2 months in Mississauga in the beginning and then sent to your home country where the processing could take anywhere from 3 months to 2 years depending on which country it is and how fast your case is. An interview would delay your application less if you have applied outland. If you are inland and go to interview, it can delay your application by as much as 2-3 years.