Pros: it's a fun alternative way to practice the normal game, as it can help you see how you could be faster at 30 FPS; and many people know about it and have tried it.

Cons: 10 FPS is sort of an arbitrary number; and it could be seen as a tool-assisted speedrun rather than a category of the game at the speed it's supposed to be played.

Is it sppedrun with 1/3 speed?

If it is i dont support

U can only think it is a way to practise but it shouldnt be a category

I don't think it should be. I agree with the pros you mentioned and that does make it a nice "mod", but they don't explain its addition as a "category". Whereas the cons do indeed explain why it shouldn't be.