Alpha Trails very slow and failing

Hi guys,

I am trying to do a particle system…with alpha triled particles…
in the main render, before i draw all particles,
i try to draw a semi transparent rectangle to get alpha trails,
This works… but the framerate drops to almost 3 - 4… ( i set framerate to 6o at start ) any suggestions on what is going wrong ?

  
  
void testApp::setup(){  
    ofSetFrameRate(60);  
    ofSetBackgroundAuto(false);  
    ofBackground(0, 0, 0);  
    ofEnableAlphaBlending();  
  
  
    toRender = 0;  
    centerX  = ofGetWidth();  
    centerY  = ofGetHeight();  
    rotation = 0;  
  
  
   for( int i = 0; i <= 4; i++ )  
    {  
        for( int j = 0; j <=4; j++)  
        {  
             p[toRender] = new Particle();  
             p[toRender]->xPos = (ofGetWidth()/4) * j;  
             p[toRender]->yPos = ( ofGetHeight()/4) * i;  
             toRender++;  
  
        }  
  
    }  
  
  
}  
  
void testApp::draw(){  
      glColor4f(0,0,0,0.01);  
      ofRect(0, 0, ofGetWidth(), ofGetHeight());  
  
     for( int i=0;i<toRender;i++) p[i]->draw();  
}  
  

:?

I also tend to get some weird flickering…