That the BS "sources" you reference (and the people who draw silly conclusions from them) ignore long-known science. Granite is one of several basic rocks that crystallize from magma. Granites often form the "roots" of mountain ranges like the Sierra Nevada and indicate slower cooling than extrusives like basalt. Maybe there are certain conditions that allow granitic crystallization to occur very quickly -- possibly changes in pressure or temperature or the sudden introduction of new feedstocks -- but I want to see original source material, not papers with the bogus "Creation Science" imprimatur which is the definition of an oxymoron.
With some effort, I managed to track it down, hoping to get some context. (You'd think that someone purporting to discuss science might provide a reference, but I guess that's too much to ask.) Anyway, the paper seems to be here, though you can't see more than the abstract without paying. He does in fact say "Geological processes are commonly thought of as slow and continuous, but many are rapid and episodic. Granitic plutonism is of the latter kind."
Without seeing the whole paper, I don't know if he claims that all granite formed quickly--which would be necessary if the creationist timeline is correct--or just that it can happen and in some cases did. Also, it's from 2005, and we don't know how it's held up over the past 8 years.
And, of course, the fact that it can form quickly doesn't mean it's not old.