Japanese can't be read as fast as English. They work differently.
English you read in a way, where you don't actually look at entire words, letter by letter. You only look at how the whole thing looks, as in words or even entire strings of words are kinda like "pictures" or whatever. It's hard to explain, but this basically allows you to "read" an entire sentence by just taking a glimpse at it. I can sometimes read the story even though a game "skips" the text, when it's in English. (i.e. when watching a speedrun) It's hard, and fails when there's a lot of lines in a textbox, but yeah. The faster you are, the less accurate it becomes, obviously, but you generally get what's being written.
Japanese is different there, because every Kanji is a picture in itself, and Katakana loanwords are generally awful, as they are no picture at all. You need to read every single kana in that case and try to think what this could refer to afterwards. Probably the biggest speed-breakers. A single Katakana word can take the time you need to read 40 words in English. This is one of the big reasons why Kanji exist, and why Kana only text reads so fucking awfully. Kana are no pictures. Kanji are.
If it weren't for Katakana words, you could probably reach the same "speed" in terms of getting information out of text, but it will still feel slower, due to Japanese text often needing less space for said information. Reading a single line in Japanese tends to tell you more than a single line in English. Thus it's rather unlikely to ever feel like you are reading as fast as you can read in English. At that point, you'd actually be a lot lot faster.