OP, it's really up to 'how' you study, not how much you study (although you'll ultimately need both). Sure some people will retain info much faster, you just have to do the best YOU can do, even if you have to study more than others.

Consider two people studying for a Calc I test. The first person studies for 100 hours but all they do is read the textbook, the second person studies for 5 hours, but does all the practice exams and memorizes the patterns for types of problems.

Who do you think is gonna do better? The second person every single time.

Also, I noticed in your post history than you're in CS or CE. In this major especially you really shouldn't compare yourself to others - it attracts hyper competitive people and the average GPA is like a 3.7 compared to the average GPA for Engineering which is like a 3.2.