CNC...speed

i have made a cnc plotter with scrap dvd drive and its working fine…but i want to increase the speed of the stepper motors…so that they can work fast…here is my code…plz note that the code is more than 9000 caracters…i i gave a little part of it

#include <Servo.h>
#include <AFMotor.h>

#define LINE_BUFFER_LENGTH 512

char STEP = MICROSTEP ;

// Servo position for Up and Down 
const int penZUp = 0;
const int penZDown =120;

// Servo on PWM pin 10
const int penServoPin =10 ;

// Should be right for DVD steppers, but is not too important here
const int stepsPerRevolution = 48; 

// create servo object to control a servo 
Servo penServo;  

// Initialize steppers for X- and Y-axis using this Arduino pins for the L293D H-bridge
AF_Stepper myStepperY(stepsPerRevolution,1);            
AF_Stepper myStepperX(stepsPerRevolution,2);  

/* Structures, global variables    */
struct point { 
  float x; 
  float y; 
  float z; 
};

// Current position of plothead
struct point actuatorPos;

//  Drawing settings, should be OK
float StepInc = 1;
int StepDelay = 1;
int LineDelay =0;
int penDelay = 50;

// Motor steps to go 1 millimeter.
// Use test sketch to go 100 steps. Measure the length of line. 
// Calculate steps per mm. Enter here.
float StepsPerMillimeterX = 100.0;
float StepsPerMillimeterY = 100.0;

// Drawing robot limits, in mm
// OK to start with. Could go up to 50 mm if calibrated well. 
float Xmin = 0;
float Xmax = 40;
float Ymin = 0;
float Ymax = 40;
float Zmin = 0;
float Zmax = 1;

float Xpos = Xmin;
float Ypos = Ymin;
float Zpos = Zmax; 

// Set to true to get debug output.
boolean verbose = false;

//  Needs to interpret 
//  G1 for moving
//  G4 P300 (wait 150ms)
//  M300 S30 (pen down)
//  M300 S50 (pen up)
//  Discard anything with a (
//  Discard any other command!

/**********************
 * void setup() - Initialisations
 ***********************/
void setup() {
  //  Setup
  
  Serial.begin( 9600 );
  
  penServo.attach(penServoPin);
  penServo.write(penZUp);
  delay(100);

  // Decrease if necessary
  myStepperX.setSpeed(1200);

  myStepperY.setSpeed(1200);  
  

  //  Set & move to initial default position
  // TBD

  //  Notifications!!!
  Serial.println("Mini CNC Plotter alive and kicking!");
  Serial.print("X range is from "); 
  Serial.print(Xmin); 
  Serial.print(" to "); 
  Serial.print(Xmax); 
  Serial.println(" mm."); 
  Serial.print("Y range is from "); 
  Serial.print(Ymin); 
  Serial.print(" to "); 
  Serial.print(Ymax); 
  Serial.println(" mm."); 
  Serial.println(" Welcome to Fuad's CNC");
}

/**********************
 * void loop() - Main loop
 ***********************/
void loop() 
{
  
  delay(100);
  char line[ LINE_BUFFER_LENGTH ];
  char c;
  int lineIndex;
  bool lineIsComment, lineSemiColon;

  lineIndex = 0;
  lineSemiColon = false;
  lineIsComment = false;

  while (1) {

    // Serial reception - Mostly from Grbl, added semicolon support
    while ( Serial.available()>0 ) {
      c = Serial.read();
      if (( c == '\n') || (c == '\r') ) {             // End of line reached
        if ( lineIndex > 0 ) {                        // Line is complete. Then execute!
          line[ lineIndex ] = '\0';                   // Terminate string
          if (verbose) { 
            Serial.print( "Received : "); 
            Serial.println( line ); 
          }
          processIncomingLine( line, lineIndex );
          lineIndex = 0;
        } 
        else { 
          // Empty or comment line. Skip block.
        }
        lineIsComment = false;
        lineSemiColon = false;
        Serial.println("ok");    
      } 
      else {
        if ( (lineIsComment) || (lineSemiColon) ) {   // Throw away all comment characters
          if ( c == ')' )  lineIsComment = false;     // End of comment. Resume line.
        } 
        else {
          if ( c <= ' ' ) {                           // Throw away whitepace and control characters
          } 
          else if ( c == '/' ) {                    // Block delete not supported. Ignore character.
          } 
          else if ( c == '(' ) {                    // Enable comments flag and ignore all characters until ')' or EOL.
            lineIsComment = true;
          } 
          else if ( c == ';' ) {
            lineSemiColon = true;
          } 
          else if ( lineIndex >= LINE_BUFFER_LENGTH-1 ) {
            Serial.println( "ERROR - lineBuffer overflow" );
            lineIsComment = false;
            lineSemiColon = false;
          } 
          else if ( c >= 'a' && c <= 'z' ) {        // Upcase lowercase
            line[ lineIndex++ ] = c-'a'+'A';
          } 
          else {
            line[ lineIndex++ ] = c;
          }
        }
      }
    }
  }
}

void processIncomingLine( char* line, int charNB ) {
  int currentIndex = 0;
  char buffer[ 64 ];                                 // Hope that 64 is enough for 1 parameter
  struct point newPos;

  newPos.x = 0.0;
  newPos.y = 0.0;

  //  Needs to interpret 
  //  G1 for moving
  //  G4 P300 (wait 150ms)
  //  G1 X60 Y30
  //  G1 X30 Y50
  //  M300 S30 (pen down)
  //  M300 S50 (pen up)
  //  Discard anything with a (
  //  Discard any other command!

  while( currentIndex < charNB ) {
    switch ( line[ currentIndex++ ] ) {              // Select command, if any
    case 'U':
      penUp(); 
      break;
    case 'D':
      penDown(); 
      break;
    case 'G':
      buffer[0] = line[ currentIndex++ ];          // /!\ Dirty - Only works with 2 digit commands
      //      buffer[1] = line[ currentIndex++ ];
      //      buffer[2] = '\0';
      buffer[1] = '\0';

      switch ( atoi( buffer ) ){                   // Select G command
      case 0:                                   // G00 & G01 - Movement or fast movement. Same here
      case 1:
        // /!\ Dirty - Suppose that X is before Y
        char* indexX = strchr( line+currentIndex, 'X' );  // Get X/Y position in the string (if any)
        char* indexY = strchr( line+currentIndex, 'Y' );
        if ( indexY <= 0 ) {
          newPos.x = atof( indexX + 1); 
          newPos.y = actuatorPos.y;
        } 
        else if ( indexX <= 0 ) {
          newPos.y = atof( indexY + 1);
          newPos.x = actuatorPos.x;
        } 
        else {
          newPos.y = atof( indexY + 1);
          indexY = '\0';
          newPos.x = atof( indexX + 1);
        }
        drawLine(newPos.x, newPos.y );
        //        Serial.println("ok");
        actuatorPos.x = newPos.x;
        actuatorPos.y = newPos.y;
        break;
      }
      break;
    case 'M':
      buffer[0] = line[ currentIndex++ ];        // /!\ Dirty - Only works with 3 digit commands
      buffer[1] = line[ currentIndex++ ];
      buffer[2] = line[ currentIndex++ ];
      buffer[3] = '\0';
      switch ( atoi( buffer ) ){
      case 300:
        {
          char* indexS = strchr( line+currentIndex, 'S' );
          float Spos = atof( indexS + 1);
          //         Serial.println("ok");
          if (Spos == 30) { 
            penDown(); 
          }
          if (Spos == 50) { 
            penUp(); 
          }
          break;
        }
      case 114:                                // M114 - Repport position
        Serial.print( "Absolute position : X = " );
        Serial.print( actuatorPos.x );
        Serial.print( "  -  Y = " );
        Serial.println( actuatorPos.y );
        break;
      default:
        Serial.print( "Command not recognized : M");
        Serial.println( buffer );
      }
    }
  }



}
  Serial.print("x1, y1: ");

Use GRBL and increase voltage.

GRBL and a cnc shield are ideal for the application you have in mind.
As Zwieblum states voltage does come into play along with and more so with current capacity of a power supply.

Be careful that you don't overload the small stepper motors from the DVD drives and let the smoke out.

If you want to increase the voltage you MUST be using stepper motor drivers that allow you to set the maximum current to protect the motor.

...R