There is a lot of advice in reddit at r/speedreading/ (some of it very good advice, some of it terrible).

Personally, I considerably increased my reading speed after using a speed reading application in my phone. I used the app only to read novels, but my reading speed with real non-fiction books greatly benefited too.

As many people have pointed out, reading faster does not always mean learning faster. However, reading is a skill that can be trained and, for most of us, there is quite some room for improvement. You can probably read faster than you do without any drawback.