User blog comment:Ubersketch/Regarding eventually computable functions/@comment-35470197-20190222005958

No, Rayo(n) is not computable by ITTM. Moreover, It is not eventually computable in your sense, because Rayo(n) itself is not definable in the first order ZFC set theory. Also, it is actually faster than FGH along ordinal notation systems for stable ordinals if we work in second order set theory or MK set theory.