DON'T CANCEL IT!
Why? Because I did and I'm pretty much messed up.
1) Go talk to an academic advisor in your faculty (I'm guessing it's Science). See if it will affect your OSAP, and what else you could add instead to make up for the 3 credits this term (ask if it's possible to add it on a PAPER FORM << exact words, k?).
2) Ask the advisor how you would find out how much of your tuition for the course you'd get back.
3) Check your desired (and even UNdesired but related) second-year program requirements and make sure none of them are Chem 1AA3. Then check that none of the courses WITHIN THAT PROGRAM require Chem 1AA3 (because you need 1A03 to take 1AA3 right...).
***That's what I didn't do, and now I'm stuck taking the "ecology" type biology courses instead of anything else (because without 1AA3 I CAN'T) to meet my required number of courses for bio. No one told me this, but if I looked hard enough I would have found that out.
4) Even if it's okay to drop the course with all of that, get a second opinion. Go to the academic office AGAIN (Rita Campbell, she gives you the shit straight-up, no two ways about it. Some other ladies there are like "It's okay if you think it's okay because it doesn't affect your enrollment/eligibility/OSAP etc" and that's not what I was looking for). Drop-in hours (Science) are from 1:00pm-3:30pm every day, and you can make appointments if you call/walk in.
5) If it's not okay to drop it for whatever reason, continue. Study with others, make a smart friend in the class that will help you, call other older students that you might now, or get together with a bunch of friends and have a group study session (really helpful!). Visit the prof's office hours and email TAs for help.
* If all of that doesn't work by the first midterm, and you fail it, get a tutor (
http://careers.mcmaster.ca/tutors) if you can afford it, maybe for some cram sessions before exams and help on assignments or even regular lesson-like sessions.
6) If you fail the second midterm, I suggest you drop ONLY then.
You're right, it sapped up my energy and time and that's why I dropped it (pretty late too), but it does have it's consequences, which you should look at first. Try hard, REALLY hard, and if that fails try again. Only after that, when you are pretty sure that you would fail the course (like me), then drop it.
Hope that helps