Is this version improved? Or it's the same version as on Steam, but without DRM?

I remember that there were several serious bugs when it was just released on Steam, including some game breaking things, such as endless loading after one of the levels.

never mind,

Would also love to know, especially if they fixed the cutscene of the third episode.

So it's the same version of the game as on Steam, with exactly the same bugs? Meh.

What DLC? I guess you are refering to the DLC for the ORIGINAL game since afaik the Nightmare Edition already contains the DLC - even on Steam. What was wrong with it? I finished the game on Steam and the only issue I experienced was loss of audio before the first boss fight afair.

Edit: Just looked it up on Steam. It seems as if some people experienced the audio problem after the third episode.

Well, it seems that the GOG version is improved / fixed.

I rushed through the first five episodes and there were no crashes, no endless loadings and no problems with audio.

As far as I remember, in the Steam version all these problems appeared somewhere between the third and fourth episodes.

The only problem I encountered is that I didn't receive an achievement for completing the fourth episode, but I think that this problem is on the GOG Galaxy side, because after I restarted the client and replayed this episode, the achievement was unlocked.

does this version work on dual core PCs? i ask this because the steam version hard locks on the third level whenever i try to play it.

Same

So similar to those games that require 60fps to run properly (hitman silent assassin) this game requires a DIFFERENT kind of bottleneck, that of the CPU...
I think QuickCPU freeware has the option to limit the CPU to one core, or perhaps it was PROCESS EXPLORER freeware. Gotta be one of those two has a FIX for this!

Windows 10 has that integrated into the Task Manager: Open the game, go to details tab in Task Manager, search for the game's process and hover the mouse over "Establish affinity".

yeah, i guess they added that. I actually LIKE the TM in win10...yet Process Explorer is still SUPERIOR...Especially when it is easy enough to integrate it with the TM as a secondary backup.