Program freezing when using Serial out

Hi guys,

This program I've made is designed to read data from a csv file and output it to an arduino (which will in turn eventually output it to a motor). Strangely, it runs just fine without the Arduino plugged in, but with the Arduino plugged in it starts freezing every one or two seconds after the first eight seconds or so. I presume some buffer somewhere is being filled up and is not clearing itself fast enough, but I have no idea where. Any thoughts?

/*  CSV_READER
    Version 3.4

    Improvements from last version:
    - 

    Improvements to be made:
    - Begins to freeze when Arduino plugged in

*/

import processing.serial.*;

int xpos=90; // set x servo's value to mid point (0-180);
int ypos=90; // and the same here
Serial port; // The serial port we will be using
Table table;
final int motorPulley = 17; //number of teeth on the pulley
final int enginePulley = 51;
final int calibrationFactor = (2880 * (enginePulley/motorPulley))/360; //2880 = max rpm of motor
int rowCount = 1;
int timeResolution; //the time interval in ms of the chosen data file
boolean fileSelected = false;
boolean run = false;
boolean pause = false;
boolean stop = false;
int time, rpm;
boolean debounce = true; //ensures button is released before it can be pressed again
int stopCount = 0; //how long before program closes
int timeRunning = 0; //time the program has spent running
int timePaused = 0;
String fileName;

void setup() 
{
  size(360, 360, P2D);
  background(50);

  selectInput("Select a file to process:", "fileSelected");
  //table = loadTable(file, "header");

  frameRate(1000); //sets framerate

  //println(Serial.list()); // List COM-ports
  port = new Serial(this, Serial.list()[5], 9600);


}

void fileSelected(File selection) //selects the file
{
  if (selection == null) 
  {
    println("Window was closed or the user hit cancel.");
  } 
  else 
  {
    println("User selected " + selection.getAbsolutePath());
    fileName = selection.getName();
    table = loadTable(selection.getAbsolutePath(), "header");
    fileSelected = true;
    TableRow row1 = table.getRow(1);
    TableRow row2 = table.getRow(2);
    int time1 = row1.getInt("time");
    int time2 = row2.getInt("time");
    timeResolution = time2 - time1;
  }
}

void draw() 
{
  while (fileSelected == false) //Does not run unti a file has actually been selected
  {
    delay(1);
  }

  clear();
  //println(frameRate); //use for testing a specific variable

  if (stop == false) //normal running section of program
  {
      if (run == true) //loads row data
      {
        timeRunning = millis() - timePaused;
        nextRow();
      }

      else
      {
        timePaused = millis() - timeRunning;
      }

      //println(rpm);
      update(0, rpm/calibrationFactor); //update serial signal being sent to arduino

      strokeWeight(10);
      stroke(0, 191, 255);
      fill(0, 0, 0);
      //ellipse(180, 180, rpm/24,rpm/24);
      arc(180,180,180,180, 0, radians(rpm/24)); //draws an arc whic represents the rpm value
      fill(255);
      text(rpm, 163, 185);
      text("rpm",166,195);
      text((float) time/1000, 30, 230);
      text("time (s)", 30, 240); //displays the time and rpm values
      text(fileName,30,30);
      text("timeR: " + (float) timeRunning/1000, 30, 260);

      if (run == false) //displays start button
      {
       strokeWeight(0);
        fill(51,255,51);
       rect(160,320,50,20);
       fill(0);
       text("START",165,332);


      }

      if (run == true) //displays pause button
      {
        strokeWeight(0);
        fill(255,153,51);
       rect(160,320,50,20);
       fill(0);
       text("PAUSE",165,332);

      }

      strokeWeight(0);
        fill(255,0,0);
       rect(230,320,50,20);
       fill(0);
       text("STOP",235,332);  

      if (mousePressed && overRect(160,320,50,20) && debounce) //detects if start/pause button has been pressed
       {
         debounce = false;
         if (run == false)
           run = true;
         else if (run == true)
           run = false;
        }

      if (mousePressed && overRect(230,320,50,20) && debounce)
      {
        stop = true;
      }

      if (rowCount >= table.getRowCount()) //end program when end of file is reached
      {
        stop = true;
      }
  }

  else if (stop == true)
  {

    fill(255);
    text("Run finished",150,160);
    stopCount++;
    if (stopCount >= 500)
      exit();
  }
}

boolean overRect(int x, int y, int width, int height) //checks to see if the mouse is over the defined rectangle
{
  if (mouseX >= x && mouseX <= x+width && 
      mouseY >= y && mouseY <= y+height) {
    return true;
  } 
  else 
  {
    return false;
  }
}

void nextRow() //loads data from the next row in the table
{
  TableRow row = table.getRow(rowCount);
  time = row.getInt("time");
  if (time <= timeRunning) //loads new rpm if we have reached that time
  {
    rpm = row.getInt("rpm"); 
    rowCount++;
  }
  if(time + timeResolution < timeRunning) //catches up if it falls behind
  {
     rowCount++; 
     println(rowCount);
  }

}

void mouseReleased() //ensures mouse is released before it can be pressed again
{
   debounce = true; 
}

void update(int x) //updates output to arduino
{
  //Calculate servo postion from mouseX
  xpos= x/2;
  ypos = y/2;
  //Output the servo position ( from 0 to 180)
  port.write(xpos+"x");
  port.write(ypos+"y");
}