Does this happen to you? You are reading a passage in English, you hit a word you do not know, you stop dead, you stare at it, and the thread of the whole thing is gone.
This is your brain's instinct
Brains are built to fix on what is unfamiliar, what is complicated, what feels uncertain.
While reading English, that means your eyes and attention keep getting pulled towards the strange words instead of making use of the familiar ones sitting immediately around them. The result is finishing a long paragraph feeling you understood nothing, even though you actually knew a good share of the words in it.
The problem is not your vocabulary. Your attention is pointed the wrong way.
Reading for gist
The skill that fixes this is reading for gist: reading for the main idea without needing every individual word.
I think it is among the most worthwhile reading skills you can build, because it changes how your brain processes text altogether.
It rests on something genuinely interesting: understanding roughly twenty percent of the words in a passage can give you around eighty percent of its meaning.
Not because you are guessing wildly, but because that is how language is structured. The words you already know are enough for your brain to assemble the overall picture, gaps and all.
Put differently, you have more to work with than you think. You have just not been using it.
How to practise
Practising this means training your brain to do the opposite of what it wants. Instead of stopping at the unknown word, deliberately move past it and keep hunting for the ones you recognise.
Three or four familiar words close together are usually enough for your brain to reconstruct the sense of the passage.
The simplest method: take any text, read it once without a dictionary, attend only to what you already know, and let your brain handle the rest.
It feels uncomfortable at first, because you are used to needing to understand everything. That discomfort is the skill forming.