Performance drop with GL_LINES? - c++

Question

I tried to draw a simple line in OpenGL:
#include "stdafx.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <freeglut.h>
float startX = -180.0f;
float startZ = -100.0f;
float qtyX = 36;
float qtyZ = 20;
float red = 0.0f, green = 0.0f, blue = 0.0f;
void init(void)
{
glClearColor(0.0, 0.0, 0.0, 0.0);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
gluLookAt(0.0, 50.0f, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -1.0);
glBegin(GL_LINES);
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(50.0f, 50.0f, 50.0f);
glEnd();
//glutWireSphere(20.0f, 20.0f, 20.0f);
glutSwapBuffers();
glFlush();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-64.0, 64.0, -36.0, 36.0, 10, 10000.0);
glMatrixMode(GL_MODELVIEW);
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(1280, 720);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutIdleFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
However, when I run the program, the performance drop significantly then after a few seconds, it stops responding (I have to run task manager and force quit the program). However, when I disable the line and draw the glutWireSphere (or a polygon), the performance is normal.
Is there a problem with my code? Or perhaps GL_LINES is deprecated?
Windows 10, 1070 MaxQ, Visual Studio