Anything that would speed up this real-time work?

I am using a very old CPU Intel Core T8100 produced in 2010 I guess, it takes 6-10s to generate a sample realtrack song(4-5 real tracks), but the CPU usage is only around 50%.

So the time consumed by BIAB loading a song is for what? Seems not only for decoding wma files to wav, otherwise it will take more of CPU usage( maybe upto 100%?).

And it is not consumed by Disk, wma size is so small, it might be the wav file generated in the realtime? But I also tried with SSD as my C drive(since someone mentioned the cache is on C drive), it didn't speed up either.

So, how could I speed up the process frown