For me, I enjoy slow reading sometimes. It's not that I can't read fast, it's just I don't want to.
Whenever I come across a great sentence, I'd pause and reread the sentence several time to appreciate, understand and memorize the beauty of words.
So reading speed never really is my biggest concern. You shouldn't get frustrated because of this too.
However, it IS important to always improve reading and analytical skills so that you can read in a speed or way as per your specific purpose.
Here are some useful tips I tried myself on improving reading and analytical abilities.
How to read
You find yourself wonder while reading probably because you haven't figure out your intention to read this book yet.
Before you pick up a book, ask yourself a question, "what can I get after reading this book?"
If you read it for fun, then it's the entertainment you'll look for. If you read it for research, then you'll search for related studies. If you read if for improvement, then you'll find methods on how to improve.
With questions in mind, your brain will automatically and actively search for answers, thus improve your overall reading efficiency.
Read the content page
If a book has a content page, read it first.
The content page consists of all the main points of the entire book. Reading it through gives you a general idea of the book, which helps you to decide quickly whether the book is worth reading or not based on your current need.
The content page can also guide you to the specific chapters you're interested into. Therefore, you only read what you're looking for.
Highlight content if necessary
In case you run into several lines where you find it hard to understand or you think the content itself is quite important, just highlight them.
The reason of doing this is to help you stay focused, while in the meantime saving the highlighted parts for later use.
Marks help you to better locate the content that matters, so you can quickly focus on what's important and the questions without reading the whole book through.
You can't rely on your brain to remember everything. That's impossible. However, you can use notes to assist your brain to remember as much as possible.
So take notes while reading. Note down what you think is important, and try to explain them in your own words. This process not only helps you to stay focused but also reinforces your memory and understanding.
If you don't want to get too distracted taking notes while reading, you can make a mind map. It's a concise and dynamic version of notes.
It's simple to create as it only consists of keywords and associations. After mind mapping, you'll get a visualized knowledge structure, which is easier to review and recall later.
Practise makes perfect. Before I work as a translator, I never intend to improve my reading speed. Like I said, I enjoy slow reading.
However, when it comes to work where I have to translate as per turnaround times for clients, I need to read and translate as fast as I can, also with quality assured.
After working for more than two years, my reading speed has largely improved. Under the equivalent degree of difficulty, I can translate few more pages within the same amount of time than before.
Read more! And you'll witness improvement.
Hope this helps!