In my first year of university, one of the courses I took was introductory physics. In high-school grade 11 and 12, I did advanced placement physics (as well as other courses) so I thought it'd be easy as I'd have a head start. I slacked off studying for the mid-term and I tanked it with a 30% worth 25% of my overall mark. I had a long assignment that I put off and did last minute, which I got 20% on worth 20% of my mark, so 45% of the mark I flushed down the drain. I tried harder and got B+ to A on the labs and weekly quizzes but they were worth proportionally very little compared to the test and large assignment I tanked. I'm not sure how well I would've done on the next test and final exam, I'd like to think I would have gotten a high mark but I was too unsure at that point so I dropped the course and never looked back. Later on, I took a few courses I knew I would do well in and got easy A, sort of, "bird courses", don't be afraid to take some later on, especially in the summer.

I mention this story as it is similar to your situation with the 2 courses. If you understand the material, then you may wish to stay in the course but if you don't understand the material and cannot find motivation, you may want to check the deadline for dropping a course without a penalty or being indicated on your transcript. It's something to keep in mind, especially if those two courses are electives. Don't hesitate to talk with the professor or TAs, they've been where you are and they managed to get through. Also, try working in a group not only for the academic benefits, rather for the social benefits and the obligation you take to keeping up to date with your work.