Skyrim’s engine is still based on Morrowind’s engine foundations, as were all other BGS games in between. This was done to save time and keep mod support mostly the same between games. Now, doing that is perfectly normal. Most companies do that, there’s no need to reinvent the wheel every time you start a new game, but Bethesda is infamous for not fixing or improving upon the major issues that plague that engine from the start, such as floaty movement and jumping physics, bad collision detection or object hitboxes, glitchy physics, outdated coding methods such as tying certain things to the framerate, limiting the indoor areas and caves to separate worldspaces from the main map and what I suspect to either be a terrible occlusion culling system or complete lack thereof, meaning the engine will tend to render things you can’t see, which is one the main causes of terrible performance on Skyrim.
I could talk all day about how incompetent that engine is and how Bethesda keeps not fixing the major issues that not even the best modders can fix but there’s no time.
That said, I’m looking forward to their announcement but I’ll be much more careful this time and not fall on the past mistakes of believing Todd Howard’s lies and getting hyped to the point of pre-ordering it as soon as I can. I really wish Beth gets their act together and invest as much time and resources as they can to make a game that doesn’t need mods to fix basic issues that shouldn’t exist in the first place.