How do I improve the tracing of drawing the path ??

[LiYaHX]

Hello, Romain Guy, I need to ask you for advice with some questions, thanks in advance.

First, I find that the path is always slower than the finger touching point when I'm drawing with finger touch, could you tell me why please?? Is it only effected by hardware??

Second, I need to achieve the function that the path and the finger touch are synchronized, could you give me some advice ??

And I tried ways below:

1. I changed View to SurfaceView at Sumsung GT-N8000(Android 4.1.2), but it does't become faster.
2. I run my demo at Nexus 5(Android 5.0), but the path is slower than the finger touching point too.(At the Android Official Document, it metions that 'Android 4.3 builds on the performance improvements already included in Jelly Bean — vsync timing, triple buffering, reduced touch latency, CPU input boost, and hardware-accelerated 2D rendering — and adds new optimizations that make Android even faster')

Thank you very much~~