setInterval(); zrýchľuje pri zmene karty(v preliadači)

var steps = 360;
var curr_dj = 0;
var speed = 20;
var timer;
var delay = 5000;
var timer2;
var slide_dir = 1;
var curr_step = 0;
var next_position;

function init(){   
   start_slide_show();
}

function start_slide_show(){
   if(slide_dir == 1){
      timer2 = window.setInterval("move_right()", delay);
      move_right();
   } else {
      move_left();
   }
}

function move_right(){
   next_position = curr_step + 90;
   timer = window.setInterval("start_animation(1)", speed);
   
}

function start_animation(dir){
   if(dir == 1){
      $('#cd').rotate(curr_step);
      if(curr_step == next_position) {clearInterval(timer);timer=null; if(curr_step == 360) curr_step = 0;} else {curr_step++;};
   } else {
      $('#cd').rotate(curr_step);
      if(curr_step == 0) {curr_step=360;} else {curr_step--;}
      if(curr_step == next_position) clearInterval(timer);
   }
}