frame rate stuck at 25

your hardware can only play at the rate it can handle.

test by putting nothing on stage and checking if your frame rate is close to what you assign in the properties panel.

if you're using as3:

import flash.utils.Timer;
import flash.events.TimerEvent;

var fps:Number;

var currentT:int = getTimer();
var currentF:int = this.currentFrame;
var t:Timer = new Timer(1000,0);
t.start();
t.addEventListener(TimerEvent.TIMER,f);

function f(e:TimerEvent):void{
fps = (this.currentFrame - currentF)*1000/(getTimer()-currentT);
trace(fps);
currentF = this.currentFrame;
currentT = getTimer();
}