Go game directory
Find nwnplayer.ini open
Find Client CPU Affinity
Write 1 for each your core

for exp.
i have 4 core 4 treat
i write
Client CPU Affinity=11111111
or
write
Client CPU Affinity=-2

no stuttering anymore

This is a red herring.

CPU affinity was only added in Patch 1.67. Before then the OS decided. AFAIK It was added so you could force NWN onto a specific core, because people claimed (unproven and lacking any sound theory why it would matter) that running on multi-core systems caused a problem, so by Default affinity forced the OS to lock it to Core Zero, so it would be just like having a single core.

But NWN a single core game. It doesn't matter which CPU core it runs on, or if you let the OS decide which CPU it runs on. It will never use more than one core at a time.

Affinity currently defaults to 0 (1st core on your CPU) which shouldn't cause anyone to have an issue. If you set this to -2 it defaults back to the pre patch 1.67 choice of letting the OS decide. This should also be OK. Note that these are pretty much the only valid options: -2 to let the OS decide, or your specific core number to pick one core to run on 0 (default) 1, 2, 3, up to your number of cores (-1). Pick a core or let the OS decide.

I never had an issue before or after patch 1.67, nor with experimenting with forcing affinity, nor letting the OS decide.

Default of 0, could only cause an issue, if you have a conflict with another CPU intensive program, that also has CPU affinity to core 0 (highly unlikely), or if you have very poor CPU cooling, and core 0 starts overheating and throttling, there is a chance that the OS shifting between the cores might keep you from throttling (also highly unlikely).

But affinity or no affinity, NWN is single threaded. It will never use more than one CPU core at a time. If you have 4 cores it will be pegged at 25% no matter how you set it up, and in any normal circumstance this is irrelevant.

NWN is a single core game. It can run on any core, but there is a penalty for having it swap from core to core to core. The OS may swap it around to make the system look like all the cores are being used. The swap takes time and slows things down. It will be faster to have it run on a single core so it won't get swapped. So setting processor affinity will help a bit.

Bullshit.

Default is already locked to a single core.

His instructions actually free it to move between the cores.

So if that was actually a problem (it isn't) he would actually be creating the problem, instead of solving it.