The application that plays the FLAC file needs to "extract" chunks of it into memory when playing. If the application is poorly written, the extraction process may use resource that will degrade the streaming output. A good example is trying to play a 1080p file on a weak CPU with slow graphics card. It is not the file but the way it is executed.
I suggest you try comparing FLAC Vs WAV with various operating systems while using different players.
I suggest you try comparing FLAC Vs WAV with various operating systems while using different players.