Being a psychic can make it hard to relate or communicate with others. When one has abilities like telepathy, precognition and psychometry, speaking out loud becomes a hassle. Perhaps this is why Kusuo Saiki, the near-omnipotent protagonist of The Disastrous Life of Saiki K, loathes interacting with his peers so much.
On the other hand, maybe he is simply stressed out because everyone around him speaks so ridiculously fast. Ever since the start of the hit series, which chronicles the daily life of the psychically-powered curmudgeon, fans have been taken aback by the lightning pace of Saiki K.'s dialogue. While this may seem like no more than a bizarre creative decision, in-universe explanations and production practices reveal a more justifiable reason for the anime's Mach speed chatterboxes.
In Episode 2 of Season 1, Saiki tries to explain some of the oddities in the world around him for the viewers. Although he has pink hair, antennas sticking out of his head and neon green glasses, Saiki passes the supposedly strict standards of the daily uniform inspection with ease. This is because he's been using his immense psychic abilities for years, subtly twisting the world's perception via mind control to make these things normal. His meddling has resulted in many quirks, such as a shift in the natural distribution of hair colors. Because of Saiki's subliminal messaging, people are now born with randomly colored hair of every hue, while plain black hair has become a rarity.
Saiki began using his abilities in this way to avoid attention and bullying as a child, but it extended much further than simple appearances. For example, in order to draw awareness away from his healing powers, he made people believe that rapid regeneration was an everyday occurrence. This had the unintended effect of altering human DNA to the point that such quick recovery became commonplace.
Along with immense feats of strength and discreet wardrobe censorship, Saiki's list of augmentations includes speeding up human thought processes. While his explanation only states that they are now able to consider volumes of information in critical situations, it is quite probable that there was some sort of bleeding effect, as with the other cases. Most likely, to compensate for the enhanced speed of their brain functionality, people began speaking at a similarly rapid rate, resulting in the whirlwind of conversation depicted in Saiki K. Though Saiki's reasons for doing so are unclear, given his personality, he may just be tired of wasting so much time with their incessant chatter.
This does raise a question regarding when exactly Saiki began the world's acceleration of thought and speech. While his flashbacks of mind control show him covering up his powers during elementary school, Season 2 of Saiki K. gives the audience a firsthand glimpse at these early developmental days.
Even when Saiki was in grade school, his peers all seemed to speak with the same reckless tempo, implying he began hurrying their reasoning just as early as he did their healing. Since Touma Akechi, Saiki's first friend as a child, speaks at a pace that even overwhelms characters within the show, it's possible he received the full force of Saiki's influence due to their close contact.
Coupled with this internal excuse for the show's lightning-fast dialogue, the anime adaptation's very nature may have necessitated such a barrage of words. The Disastrous Life of Saiki K was originally produced as a series of five-minute shorts before getting a standard length production. These miniature vignettes are what make up each of the five segments in any given episode from Season 1.
Season 1 consists of 24 full-length episodes, meaning it initially equated to a whopping 120 shorts -- each of which had to pack a fully cohesive storyline into five short minutes. Given the highbrowed jokes and complicated explanations Saiki K. is known for, hastening the dialogue may have been the only way to cram the entire gag into such a short duration.
