I used to not subvocalise (have inner voice) when I was younger and I used to read way faster than I do right now. With that being said, if something works for you don’t change it. I don’t think subvocalisation is your reason for bad comprehension. If the inner sound is causing you annoyance, then you can listen to atmospheric BGM music that suits the book using earphones/headphones. It helps me when I feel that my voice is really loud and distracting. There is nothing wrong with writing down character names, places and major events after you finish your reading session. It will improve your recalling abilities. Might be tedious at first but it’s a good exercise. Good luck and happy reading!