I try to port to arduino. but speed is slower than native code.
I think. There are a process running on background.
Is it posiable to break process when plot data to screen?
You could use noInterrupts(); and I don't think anything would run other than your code but I doubt that's the problem. What are you comparing to code-wise and how big a difference are you seeing?
I'm thinking it's something to do with using arduino/wiring function calls vs native c or machine language.
For all practical purposes, there is NO "background process" in arduino.
However, the level of abstraction provided by an arduino function call like digitalWrite(pin, val) makes it MUCH slower than something like "sbi PORTB,4" About 20x slower.
There has been a fair amount of discussion on this in other threads. http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1230286016