title: Pygame - blit is causing lag
body: <p>I am making a simple platformer game, when I add a background using <code>pygame.surface.blit()</code> it causes a lot of lag, However when I use <code>pygame.suface.fill()</code> it runs at ~120 fps.</p>
  <p>How do I fix this?</p>
  <pre><code># map vars
  mapFloor = []
  ground = 700
  mapController(True)
  bg1Colour = bg1Colour = transform.scale(image.load('assets/PNG/Backgrounds/set1_background.png'), (1280, 1024))
  bg1Colour = [bg1Colour, bg1Colour.get_rect()]
  bg1Tiles = transform.scale(image.load('assets/PNG/Backgrounds/set1_tiles.png'), (1280, 1024))
  bg1Tiles = [bg1Tiles, bg1Tiles.get_rect()]
  bg1Hills = transform.scale(image.load('assets/PNG/Backgrounds/set1_hills.png'), (1280, 1024))
  bg1Hills = [bg1Hills, bg1Hills.get_rect()]            
             
  
  
  while not finished:
  
      for events in event.get():
          exiCheck()
          playerController(True)
  
      surface.blit(bg1Colour[0], bg1Colour[1])
      surface.blit(bg1Tiles[0], bg1Tiles[1])
      surface.blit(bg1Hills[0], bg1Hills[1])
  
      mapController(False)
      player = playerController(False)
  
      display.flip()
      clock.tick(120)
  </code></pre>