Shaders Cleaner for P3Dv5 is now ready for download from the Freeware Section in my Store.  It is downward compatible to version 3, which I don’t think anyone still running it, however.

NOTE that after the shaders are cleaned, it may take a bit longer for P3D to reload the flight session the next time.  The screen may even black out for some seconds.  No worry, everything will come back to normal after the shader cache is built again.