The first thing you need to understand before being able to learn faster is that the sum of the information your nervous system processes it responsible for the reality you are aware of. The following is an ever-evolving collection of methods and tools, which makes use of the human capacity for learning to the authors current knowledge. It is up to you to balance and curate the information content.
To prioritise information distribution, scientific references are currently limited and will be added over time.
In school, we learn to pronounce each word as we read it. This involves the unnecessary process of simulating our entire process of vocalisation. If we take it away, we can process words and symbols at a much faster pace.
You can practice speed reading by distracting your mind from pronouncing any word by pronouncing "1-2-3" or "a-b-c" over and over in your mind while scanning through the text. Over time you will notice that you still internalise the information, while not pronouncing each word. As you get better, you can silence your mind and read only with your eyes. This works especially well for popular science books, easy literature and fiction.
SwiftRead offers a Chrome plugin that scans the current webpage for an article or text and quickly flashes each word. This can also be good practice.
For more complex topics it's helpful to involve more senses of perception, auditory being the most accessible.
Read Aloud is a Chrome plugin that scans the website for text and reads it out for you. You can adjust the speed of reading to involve your auditory sense.
Android has an app called @Voice Aloud Reader which can read eBooks and PDFs.
Most video players have a speed control that has a limit at 2x the original speed. Some videos are still too slow, so there's an app to increase video playback even further called Video Speed Controller.
It also helps turning on subtitles sometimes.
Memorisation depends on several factors involving the release of chemicals the brain at a specific area and time. Some can be influenced and controlled, especially after around age 25.
Making a conscious effort to connect intangible data with visual, auditory or kinesthetic imaginations is called "mnemonics". One of the most popular books on this topic is called "How to develop a perfect memory" by Dominic O'Brien. It will teach you how to remember numbers, dates, names, events and similar data very fast.
The Feynman Technique was popularised as an aid to memorise content better by writing. There are a few key points:
Before reading, write a question that you think the text should answer
During reading, make sketches to visualise what you read
Keep writing down questions with each chapter. Answer them once you find an answer.
Summarise what you read if necessary.
Here is an overview on how to read a scientific paper with ideal retention and curation of the content.
Feynman also believed that having a mentor is just as important as having a mentee. This helps asking domain specific questions about to a friend (mentor) and after internalising, explaining the content to another friend, who might be interested in the content. During explanation your mentee might ask you questions for clarification and you will notice where you have knowledge gaps.
Exercise increases blood flow and the release of growth factors in the brain. Sleep and non-sleep deep rest (meditation, yoga nidra) enables the brain to make long-lasting connections through a process called neuroplasticity. Nutrition based on unprocessed foods low in sugar accelerates your bodies regeneration.
It is needless to say, that good sleep, exercise and nutrition are important. But so is the timing. As our bodies are exposed to the circadian rhythm of the environment, the peak mental capacity also shifts. It is also very individual and can be self-analysed. A few templates and instructions are in the book When by Daniel Pink.