The removal of saccades is a factor, but it's not the main factor based on what I've studied about speed reading.

When we learn to read, we often vocalize sentences in our minds, and furthermore, our brain has the capability to recognize words in rapid succession faster than we usually read them.

In order to read faster, you're taught to "see" the whole line very quickly and take in the words faster. You still read from left to right, but you do it at the maximum speed, avoiding mental vocalization of the words. But then you have the problem of focusing on your speed and that makes it harder to focus on comprehending what you're reading. Also you might read too fast to comprehend.

A mechanism that shows you word after word based on data estimating the time you actually need to comprehend the word - and no more - allows you to speed read without trying, without going faster or slower than you should.

One more thing I'd point out is that the brain is also really good at recognizing word groups, so although you'd have your saccades described in Eleonora's answer, using the same concept of flashing words one at a time could be modified to flash groups of words and possibly improve speed and comprehension further.

Saccades are a factor, but it's not the main factor based on what I've studied about speed reading.

When we learn to read, we often vocalize sentences in our minds, and furthermore, our brain has the capability to recognize words in rapid succession faster than we usually read them.

In order to read faster, you're taught to "see" the whole line very quickly and take in the words faster. You still read from left to right, but you do it at the maximum speed, avoiding mental vocalization of the words. But then you have the problem of focusing on your speed and that makes it harder to focus on comprehending what you're reading. Also you might read too fast to comprehend.

A mechanism that shows you word after word based on data estimating the time you actually need to comprehend the word - and no more - allows you to speed read without trying, without going faster or slower than you should.

One more thing I'd point out is that the brain is also really good at recognizing word groups, so although you'd have your saccades described in Eleonora's answer, using the same concept of flashing words one at a time could be modified to flash groups of words and possibly improve speed and comprehension further. In fact, I'm sure I've seen an app somewhere that does just that.