Suicide is not a solution for any problem. There is no big issue about weakening in some subject. If you already know that you are lagging in some subject then you can work hard and can be very good on that subject.
I know it is not an easy work to deal with all subjects at the same time, but imagine what will happen after your this decision, this can break your parents and others will laugh as well that you’re a loser. I am not saying that you have to work hard because of those people. But work hard for yourself and your parents who have many dreams for you.
You can simply hire a tutor who can help you to achieve good grades and enhance your learning ability.
Work Hard, Be Positive.
Hope to hear from you soon.