Tracido: I am not a software developer. I still know all tech demos are done on special hardware setups, not normal PC's, not optimized.
Well, more importantly, they are quite simply not done. I have no idea how Witcher 3 development went, but let's make an example:
Devs show a playable demo in which you see a beautifully rendered village, grand vista with seemingly vast plains and massive cities in the distance, and they show you how the main protagonist talks to a bunch of NPCs, how those NPCs walk around the village, and then show some combat.
Now, what happens is that they have some NPC pathfinding done, some scripting so they can show off NPCs "going about their lives" or whatever, they have grabbed bits of combat systems and monster AI from Witcher 2 and built upon it a bit to show off basic concepts of the combat, and that's it. Not only is the game presented on a massively overpowered rig as to not run into any performance problems, all that rig has to calculate is the tiny slice of what they have decided to present.
When it comes to the finished game, however, things are suddenly a lot more complicated. I have no idea of Witcher 3 featureset and I most certainly do not know how it had been achieved, nonetheless, in the finished product, the presented slice of the world is suddenly expanded upon massively - suddenly, what those NPCs do is not just pre-scripted, but calculated to some extent, based on a bunch of variables. Geralt's beard is growing, presumably the game keeps track of various happenings around the world, there's a ton more AI calculations it needs to be doing for opponents, and even in the biggest pitch, the game needs to run smoothly on a computer fulfilling minimal requirements. The difference is massive.
Supremtin: oh really, funboy you will believe every shit they tell you
Funboy me does like to laugh. Thank you for providing in spades :-)