I've had issues with running NWN1 on Windows 10 and basically every version all the way back to when I started playing around 2005. I think I got it figured out now though by using a program called Latency Monitor to determine if your PC will run in real-time. I find that the game is heavily dependent on your CPU and I have an old PC from around 2014 that is newer than the original PC I started playing in 2005, but it still had issues.
https://resplendence.com/latencymon
Once installed open up the program and click the green play button and see if your PC will run in real-time if bars don't go into the red and now stays in the green then you are good, if this isn't the case then you need to optimize your PC for real-time. If this isn't the case then search for making your PC real-time on Google. The program will indicate under "highest reported ISR and DPC routine execution time" that is causing a slowdown on your PC. You can also go to the processes tab and check which processes are causing hard page faults.
Here are the Windows tweaks I did.
1. Make sure Windows is running your game in high performance graphics mode.
https://www.top-password.com/blog/enabl ... -or-games/
2. Then put the PC in high-performance or Ultimate Performance mode.
https://www.aomeitech.com/windows-solut ... ws-10.html
3. This was one of the biggest improvements. Make sure the game is running in "high priority mode for processing".
"Every program in Windows has a priority level that determines how much of the system's processing power it receives when more than one program has processes running at the same time. If you're playing a game without running any other programs, changing the priority of the game will have little or no effect. On the other hand, if you also have processes running in the background, boosting the game's priority tells the computer to make sure it plays smoothly, even if it means slowing down other work."
https://www.techwalla.com/articles/how- ... h-priority
The directions say to use above Normal but for my system, I went with real-time and found that to work the best. Note you won't see the NWN1 process till you have the game running and Alt+ESC out of the game back to the desktop.
It also helps to make sure the video card drivers are up to date.
These steps helped out a ton but I still get a few issues where the game loads information and it bogs down in the Faerie Gardens, but the processor went from loading everything on one core, maxing it out, to evening it out over all 8 cores.