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(Updated 28/6/2014..screen cap incorrect now)

Long time readers know that I use a Windows command file to run FSX. There are a couple of reasons for this. Firstly, I use SimLauncher by Maarten Boelens as a front end interface to load a flight directly into FSX. After configuring the flight, SimLauncher executes the command file with the name of the .flt file to start FSX. SimLauncher has a lot more options for starting a flight, like the state of the plane’s systems.

Secondly, and more to the point of this post, the command file sets the processor affinity and thread priority on FSX and all the FSX related processes. Using the command file, I give FSX.exe free and exclusive use of multiple cores and have it run at a higher priority than other programs. The batch file has been working very well, thank you, for almost 2 years.

Recently, I updated my Nvidia video drivers and installed GeForce Experience software. The GeForce Experience application includes ShadowPlay, Nvidia’s native video recording software. ShadowPlay works great..BUT, the extra Nvidia “stuff” running in the background of GeForce Experience was noticeably hurting my FSX performance. Background processes such as checking for driver updates that are really not needed.

I tried to turn these processes off, but GeForce Experience, and by extension, ShadowPlay would not start without those executables running. So began the experimentation with affinity and priority in an attempt to at least confine those programs to only a small part of the processor.

Last year, in a forum thread on using FSX’s native processor affinity settings, Simmer2050 (not his real name) indicated he used “ProcessLasso” to set the processor behavior of FSX. At the time, I was happy with the way my command file was working and mentally filed the thread away for future investigation. Turns out, ProcessLasso is exactly what was needed to tame those Nvidia programs.

ProcessLassoas it is running on my system

Some things to note from the image:

  • FSX.exe is the only FSX related software running on cores 1-6 of my 8 core machine. It is also running at a “High Above Normal” priority.
  • All other FSX related programs are confined to core 0 (the first core). Except for TrackIR, all are running at “Normal” priority.
  • The Nvidia apps are confined to core 7 (the last core).

With this configuration, no FSX related app is going to take processor capacity away from FSX.

The basic version of ProcessLasso is free and can be found at If you are interested in this arcane sort of knowledge, give it a try.

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