Why does Nietzsche call Plato a bore?

Question

There is this quote attributed to Nietzsche saying 'Plato was a bore', though I do not seem to be able to find the source for this at this moment. Assuming he did say this, why was this?

A few posibilites I could come up with from likely to less-likely:

One, is this due to the fact that plato believed in 'another world' apart from our world? He believes in ideals and something 'true' whilst Nietzsche opposed this? I think it could be due to Nietzsche advocating the uncertainty, where Plato thought there was something absolute, this is disregarded now by Nietzsche (or we could not reach it if there was).

Or secondly, perhaps it follows from Nietzsche's "The Birth of Tragedy", causing him to compare Plato with the greek figures from apollonian or dionysian characters, and drawing the conclusion that Plato did not have an as interesting life as either those characters or as the writers. [This seems a bit far-fetched, it would not be fair to compare Plato with characters from stories]

And thirdly, Nietzsche wanted to be a modern kind of Plato, a man of similar importance to philosophy but wanted to make it clear that he is NOT plato, and that their views are incompatible.

Answer 1

Nietzsche writes in the second aphorism from the section What I Owe to the Ancients of his work Twilight of the Idols, or, How to Philosophize with a Hammer (1888):

I am a complete skeptic about Plato, and I have never been able to join in the customary scholarly admiration for Plato the artist. The subtlest judges of taste among the ancients themselves are here on my side. Plato, it seems to me, throws all stylistic forms together and is thus a first-rate decadent in style: his responsibility is thus comparable to that of the Cynics, who invented the satura Menippea. To be attracted to the Platonic dialogue, this horribly self-satisfied and childish kind of dialectic, one must never have read good French writers — Fontenelle, for example. Plato is boring [my emphasis]. In the end, my mistrust of Plato goes deep: he represents such an aberration from all the basic Greek instincts, is so moralistic, so pseudo-Christian (he already takes the concept of "the good" as the highest concept) that I would prefer the harsh phrase "higher swindle" or, if it sounds better, "idealism" for the whole phenomenon of Plato.

Nietzsche considers Plato boring due to his style of writing in his dialogues. But Nietzsche's rejection of Plato goes deeper and is based on the content of Plato's philosophy, see the quote.

The quote above partly supports your first proposal. But it does not support your proposals two and three.