I only read books in English and I keep my phone nearby to lookup words if I don't know their meaning and they seem important to the story (most aren't though). 95% of books I get through without looking up a word. But I also want to mention that some writers or books are just harder to read because of they way they are written. There is nothing you can do about that, and if it stops you from enjoying the book then just don't read it. There is nothing wrong with that.