Why is KNLMeansCL slowing me down so much

[Selur]

What I could gather:

• Last KNLMeansCL (https://github.com/Khanattila/KNLMeansCL/releases) version is from 2018 and Hybrid hasn't changed it's code related to it even longer.
  Starting 2015 KNLCMeansCL required at least OpenCL 1.2 support. -> you can try whether using the 0.6.11 version helps with your problem.
  
• It's normal that 'CPU' mode doesn't work on non-Intel system, since AMD dropped CPU support for OpenCL.
  
• I attached a small .exe which one can run from a Windows Command prompt and that should list the OpenCL capable devices.
  
• To run OpenCL on Intel CPUs one needs the Intel® CPU Runtimes for OpenCL™ Applications, note that this is really slow and will run OpenCL on the CPU not the GPU which might be on the CPU chip.
  Even old NVIDIA Kepler-cards (and newer) are way faster than running OpenCL an Xeon systems.
  

I still can't properly explain why KNLMeansCL suddenly stopped working on your system, my only guess is that the drivers on your system changed.

Cu Selur