It used to be a huge concern for me as well. I realized that the more I read, the faster I read. So if you are worried about reading speed, don't. Just read, and it will get better. With no extra effort from me, my reading speed increased by at least 50% since I started reading books seriously.
I'm not really worried about how fast I am, I'm just curious how fast I am in comparison with others. (I am fast enough for my needs)
Somewhere around 400, 450 words per minute for fiction and non-technical non-fiction.