Any time I pause the game with the space bar, or even to go to the pause menu with ESC, the game lags terribly. Accessing my inventory or spellbook, and then targeting a PC is boggy and completely useless. Resuming the game with space bar makes everything run fine, no lag whatsoever, but this leaves little time to reach for a quick potion or scroll.

Any help with this will be much appreciated.

I actually have the same issue, and am also looking for an answer, but here is what i know so far:

1. This happens on my laptop running intel HD 4000 graphics, and a multi-core processor.
2. This does not happen on my surface pro which runs intel HD (regular version) and a single-core processor.

I higly doubt that any other hardware components besides these two would matter much, but if it isn't the above two, my next guess would be the drivers. What does your system look like?

I'm running it on a modest desktop. Windows 10, Intel Pentium Quad Processor, Intel HD Graphics with recent drivers. And there's no lag when the game isn't paused. I don't understand how it seems so bogged down when there's nothing happening in the game.

Ok, well, it's probably because we use more than a single core processor in the machines where it doesn't work then. GOG actually wrote something about this potentially being a problem, but the method they suggest for devoting less cores to a task doesn't work on my computer (it looks like it needs to be done differently on W10.)

I'll see if i can figure something out and then I'll let you know.

I'm getting this issue as well. I'm running the game in single core mode via Task Manager and I'm running the game in compatibility mode for WIndows XP SP3