Performance of custom audio effect module

[Wanzhang Huang]

Hey guys, I have created my own audio effect module, and run happily in high-performance CPU(Amlogic S905, 1.5GHz, quad-core processors), but bad user experience in low-performance CPU(Qualcomm APQ8016, 900MHz, quad-core processors) . The output audio has a stutter and plays slowly. We know that audio effects are running in a mediaserver process, and I check the CPU usage when playing. It occupies only 35%, but the idle process still has 57%. So my questions are:

1.What causes the audio stutter?

2.Since CPU is not fully used, does it possible for the mediaserver process to take more CPU to do audio processing? 

3.What is the proper way to improve performance of custom audio effect module?

Hope for replies.