adjusted buffers to increase performance

[empirephoenix]

Hi,
i basically just tested a bit around with somewhat current hardware (i7 6000 generation) what size of buffer seems to allow a good tradeoff between performance and memory useage.
Increasing the buffers as done here, increased the performance for larger files (>prior buffer) multiple times, eg a 500mb mp4 downloads with 100MByte/s instead of 1Mbyte/s.

[kzahel]

That's a ~67MB read buffer and writing 4MB at a time.
Thank you for doing the performance testing.

I will check it out and test locally and see how it goes when I get the chance soon