You said that you play a lot of Rome 2, did you play that game on launch day back in 2013 or so?
It was, uh, well...Pretty damn broken. To put it into perspective turning the graphics to maximum high-ultra or whatever flipped something somewhere that made all of the unit models use the LOD system in such a way that the super low quality LOD for soldiers at a distance was the only one used at all. It also took a good 5 minutes to resolve a turn. And my god, the game wrecked my PC with the lamest frames ive seen in a while. The rumour was that it was rushed out by the publisher for Christmas, and as a result I won't be pre ordering from Creative Assembly ever again, however good their new Warhammer Fantasy game may look.
Comparing it to Fallout 4 is really no contest. Everyones experiences may differ, of course, PC hardware is pretty fantastically crazy in that way, but while Skyrim was actually the smoothest launch for me its been relatively unbroken for Fallout 4. And even with Rome 2 the game got some intensive patching, and now the vast majority of those problems are fixed. I have no doubt we'll be getting some intense patching for Fallout 4 aswell.