A blind child can learn to read braille just as efficiently as a sighted child can learn to read print.
With proper teaching and enough time to practice, most students can learn to read and write braille at a similar speed to other children learning to read and write. This is dependent on a child being well taught and having enough time allocated to learning braille as an essential skill rather than an added extra.
Reading print quickly and efficiently comes from years of training, experience and a love of reading. The same is true for learning braille.