He didn't stutter when speaking. He just couldn't read as fast as he was talking so he had to stop every few syllables.

In other words, he was 17 and couldn't read fluently. But he wasn't stupid. He was quite conscientious about his side business and bookkeeping.

ps: I stuttered when I was a child.

The English word you want is not stutter, but stumble. Stutter (or stammer) is a medical condition, stumbling over words is the result of a poor quality education.

Thank you, I edited my original comment.

Not a problem. English is an easy language to begin, but a very hard one to master.

I knew the correct word and expression, I just didn't have it in mind at the right time ^^

I've read and written in English everyday for 10 years. I just can't speak it. One day I realized most news article I read were only translations of other articles. So I decided to skip the middle man.

Any chance he's dyslexic or similar? That description kind of sounds like it.

>He just couldn't read as fast as he was talking so he had to stop every few syllables.

Is that your professional medical opinion?

No. But it's the opinion of someone who spent 6 to 8 hours a day during three years with the person in question. He couldn't read. When he read in his head he mouthed the words.