it really is a question of track. a lot of the kinks (Portarlington, Ballybrophy, Lisduff) have been ironed out. problem is that quite a lot of the midlands is pure bog.
the bit from Ballybrophy - Thurles is on the least boggy part (which is how Templemore ended up with a station as they curved around the very soft bits) but it is still soft. The newer ballast laying machines are a great help, also new type of stronger rail.
till this is sorted you wont be doing 200 in any long burts anytime soon.
We are the passengers