Slow reading is not simply reading at a lower speed. It is the decision to stay with a text long enough to notice its structure, uncertainty and language instead of extracting only the quickest available point.

Some Texts Resist Speed
A news update can be skimmed. A difficult essay, novel or work of history often cannot. Arguments unfold across pages. A sentence may change the meaning of an earlier one. Characters become clearer slowly. Reading at the same pace in every situation therefore makes little sense.
Slower reading creates room for rereading, annotation and disagreement. It also allows a reader to notice when they have not understood something instead of moving on because the page has technically been completed.
Attention Is Not a Moral Achievement
It is easy to turn slow reading into another self-improvement project. That misses the point. Not every book deserves close attention, and there is nothing virtuous about spending an hour on a page that offers little in return. The useful distinction is between choosing speed and being unable to vary it.
Digital reading has not destroyed deep reading, either. Screens can support serious work; printed pages can be skimmed carelessly. What matters is the reading behaviour, the purpose and the amount of interruption surrounding it.
The Value of Leaving a Thought Unfinished
One advantage of reading slowly is surprisingly simple: a book is allowed to remain in the mind between sessions. A difficult claim can sit unresolved overnight. A paragraph can be returned to later. The reader does not have to produce an immediate opinion.
That kind of delay is useful in academic life, but it also matters outside it. Some books become more interesting precisely because they refuse to be efficiently processed.