Even though CPU have hardware support for decoding, there are factors that can affect how much the computer handles it. The games have to deal with multiple la

Even though CPU have hardware support for decoding, there are factors that can affect how much the computer handles it. The games have to deal with multiple layers of audios at the same time. So imagine one sound file have the dialogue for that specific scene, other sound file have the ambient music to compliment the surrounding, other file have sound effects, etc. So the games have to handle maybe 10 audio files at the same time which can put the strain on the CPU since it need to handle the decoding for compressed format. When that occurs, it eats up the CPU resources when it should be allocated for other stuff. Also don't forget some game have 5.1, 7.1, Dolby variants, etc which can be taxing on the CPU if it have to process multiple compressed audio at the same time.