I enjoy reading theories and concepts, but I also struggle with reading heavily detailed content as well, especially history because there is an overabundance of facts, one after the other without explanation. The following tips have helped me.
Segment the writing. Globs of text are hard to filter because they present so much detail at once, sometimes without explanation. It's just fact after fact after fact. Tedious writing is also difficult because it simply states facts without narrative or story behind it. In other words, the big picture or overall meaning is unclear, so it's hard to process the details.
To begin, don't always start reading from the beginning. Flip through the article, book, or section and read a passage which catches your eye or interest. Skip around and read what interests you most. Research a few terms or facts online between readings. This makes reading more interactive, and fun.
If you want a more structured approach, try this. Break down the chapter, section, or article you are reading into parts. Organize those parts by themes. Then, determine the main idea or purpose of the first section in the article or passage. Identify the main idea or topic sentence/thesis, and set this aside from the supporting details. This way, you're not paying attention to every single detail all at once. If the text is available online, copy it in parts to a Word document, and read it there, using colored text or highlighting to feature passages which stand out as significant because you have a question about it or you want to explore this idea in more detail.
Don't worry about remembering the information when you read it the first or second time. This is the biggest mistake made by readers of dense material, they worry too much about remembering rather than reading to understand. First rule is read just to get a sense of the passage, not to store information or amass data. Don't stress yourself out about it. Don't worry about remembering or paying attention to every detail or fact. If you are new to the topic or subject, just read for general knowledge or reference. Later on when you are more familiar with the area, you can embrace the details.
All the best!