When turtle_screen.tracer(0) is typed on the editor and the file is executed, Turtle Graphics Window is not responding.

from turtle import Screen, Turtle

screen = Screen()
screen.setup(width=600, height=600)
screen.bgcolor("black")
screen.title("My Snake Game")
screen.tracer(0)

starting_positions = [(0, 0), (-20, 0), (-40, 0)]

segments = []

for position in starting_positions:
    new_segment = Turtle("square")
    new_segment.penup()
    new_segment.color("white")
    new_segment.goto(position)
    segments.append(new_segment)

game_is_on = True
while game_is_on:
    for seg in segments:
        seg.forward(20)

screen.exitonclick()

After running and waiting for some time, here is what I am getting:

Please, can someone resolve this issue?