#include 
#include 
AccelStepper stepper(1, 9, 8); // mode 1 = half-step, etc... 200 steps/revolution
                               // pin 9 = PUL 8 = DIR

void setup() {
  stepper.setMaxSpeed(4000);
  stepper.setAcceleration(2500);
}

void loop() {
// screw pitch = 2.5mm/rev, motor = 200 steps/rev + 1/2 step mode = 400 steps/rev
// 30mm travel = 12 revs / 200 * 2 * 12 = 4800 steps

   // slow speed drilling 
   stepper.moveTo(-4800); // position +30mm drilling 1/3 
   stepper.runToPosition(); 
   delay(250);            

   // fast speed movement 
   stepper.moveTo(0); // position 0mm / chip removal
   stepper.runToPosition();
   delay(250);

   // fast speed movement 
   stepper.moveTo(-4800); // fast advance to +30mm for drilling 2/3
   
   // slow speed drilling 
   stepper.moveTo(-9600); // position +60mm drilling 2/3
   stepper.runToPosition();
   delay(250);

   // fast speed movement 
   stepper.moveTo(-4800); // position +30mm / chip removal
   stepper.runToPosition();
   delay(250);

   // fast speed movement 
   stepper.moveTo(-9600); // fast advance to +60mm for drilling 3/3 
   
   // slow speed drilling 
   stepper.moveTo(-14400); // position +90mm drilling 3/3 end of drilling
   stepper.runToPosition();
   delay(250);

   // fast speed movement 
   stepper.moveTo(0); // return to starting position
   stepper.runToPosition();
   delay(250);
}

I defined two speeds (FAST_SPEED and SLOW_SPEED) to differentiate between fast movements ie chip removal or advancing and slow movements, drilling.

So bfore each movement, setMaxSpeed() is called to dynamically change the speed based on the task. The slow speed is applied for drilling operations, while the fast speed is used for moving between positions