>Your time is a precious, limited resource. Get to a point where you don't screw up on a test and then switch your attention to much more important endeavors. [...] Other than research projects, get involved with some group of people on side projects or better, start your own from scratch. Contribute to Open Source, make/improve a library. Get out there and create (or help create) something cool. Document it well. Blog about it. These are the things people will care about a few years down the road. Your grades? They are an annoyance you have to deal with along the way. Use your time well and good luck.
While probably 90% of undergrads undershoot in terms of time spent on their courses, the other 10% "Goodhardt" their grades and misallocate their time and abilities.