Not really?

Experiencing the file of a book might only take him a few seconds, but unless his mind's basic clock speed is much faster than ours, parsing and absorbing the thoughts imparted by said book should keep him occupied for a fair while. Downloading isn't the same as reading.

Or he can also think in parallel, something organic minds are incapable of. I mean, he does think faster, but nowhere near anything extreme like "subjective day in a second"

Mmm, I still don't think you could properly absorb a book by breaking it down into sub-minute thought tasks and running them all at once. I make no claim to understanding the informational and psychological theory involved, but my gut feeling is that you would hit "irreducible linearity" long before that.

Either way, though, it makes me giggle a bit to imagine ACs basically writing and reading the literary equivalent of a Black MIDI.

Also, I really ought to read some Lem works sometime. I gather he was a pretty major influence on Orion's Arm, which I already read and enjoy.