Over 95% of the time. A small brief rare stutter might be unavoidable when a bunch of aircraft spawn or an atomic blast occurs. LOL. Even "The Black Death" track, which has become a significant universal benchmarking mission among AAA members, has no stuttering for me in IL-2. Almost everyone can see huge improvements.
The nHancer made the biggest difference for me.
Also, to completely clear (move to another folder, including shortcuts) all the stuff on the Desktop will directly improve the stuttering issue for most simmers. For some, it makes little difference. For me, it was drastic improvement.
The nHancer allows me to make different profiles for various purposes. When I want the smoothest running, I manually start the DirectX profile. When I need best image for movies and screen captures, I manually start the OpenGL profile. I only need to manually start the OpenGL because I need to switch between DirectX and OpenGL before starting IL-2. Otherwise, OpenGL profiles activate automatically upon starting IL-2, unless DirectX has been used just prior to that. Now I have a powerful Centrol Control Center for Optimization: nHancer.
TIP: Many guys have a condition in their computer which causes processing lag and instability.
Leatrix Latency TCP, or other similar program will stop the lag-dead. It worked in my PC and I saw the latest jump in smoothness, especiallly with online flying.
Avaro, fabulous help. I would like to see guys keep this kind of info coming and easy to find in the Forum for people seeking smooth IL-2 running.