There are special reading trainings available online to enhance one’s reading technique and speed. Plus, you can do some basic things to train your mind analyze the information and structure it out. Once you learn how to do that, your brain would fish out the key facts and information out of what you read and remember it.
One of the simplest things to do is to read smaller passages and then summarize them out loud or write short resume on what you just have read. Then go back, read the whole thing over and compare with what you were able to grasp.