Can democracy make our society stable?

Due to the environment I have grown in, I have to admit that I’m not very familiar to the democracy society. However, based on my experience and new knowledge in Singapore, I think I like democracy, but I really do not think that democracy can always make the society stable.
Firstly, I want to point out the problem of efficiency. I do not think the efficiency of the democratic government is better than other politic forms of government. As we have the democratic government, we always have strong opposition, and they question the validity of most of the policies that the governments made. I am not saying that I do not like these oppositions, but in fact the efficiency of the government were really pulled down by it, I think most of the time it is a little waste of time. Wasting time is wasting the money of the tax payers. The aims we tax payers pay the taxes are not for the politicians to argue and argue. Most of the time, the purpose they agree or disagree on some policies are just based on their benefits. So, we can see that in some democracy country and district, people are not aware of what the policiy like, such as Italy and Taiwan. In Italy there are always 2 parties argue with each other and want to get the majority in the congress, and make the efficiency of the government lower and lower. This situation make some of the voters tired of the change of the governments and lost their heart on the policy and government, and I think this situation will make the society unstable, and may cause the conflict( although it is not very possible.)
Secondly, I think the democracy is the game of majority, if you are the majority, you will own the whole country. We cannot deprive the rights of the minority to satisfy the majority, it is quite unfair for the minority and will have a high possibility of conflict. The situations of conflict in Sri Lanka, Northern Ireland and the racism in America are very good examples of it. The majority always abuse their right to get benefits from the minority. I cannot find any good solution for it. Maybe we should wait for a superman to solve it.
All in all, I think the democracy may also have many problems to solve, it cannot always be stable, but comparing with other policies, maybe it is the best policy that occurred.