Science is slow for sure. You need to gather samples and run tests. Often testing for causality is impossible, because you literally need to "cause" the issue in your sample group and that raises ethical issues if the thing you're "causing" is harmful.

It's not even the human parts that are flawed with science either.

Science is fundamentally flawed by nature because in science and therefore reality as you know it you cannot prove anything to be true. You can only falsify things in science. Proof is the domain of mathematics.