Hi All! I've used !SlickMenu by Compojoom (GNU/GPL) on my non-commerce site, but this script has very low speed in Opera and Firefox browser. Especially it gives trouble Opera netbook users, the ones who work on slow computers. But in IE8/9 this script hasn't have any problem on netbooks.

This script icetheme studio (icetheme.com) used in most template too. And dropdown menu in all their templates have very low speed on notebooks in Opera too.

Do you have any idea?

PHP Code:
<?php
/*
 * Copyright(C) Compojoom.com. All rights reserved.
 * License http://www.gnu.org/copyleft/gpl.html GNU/GPL, see LICENSE.php
 *
 * !SlickMenu is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * !SlickMenu is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

header('Content-type: text/javascript');
$id = (int)$_GET['id'];

if (!
$id) {
    echo 
"alert('No ID provided!!!');";
    exit;
}
$js '';
ob_start();
?>

var SlickMenu<?php echo $id?>={};

SlickMenu<?php echo $id?>.accordion=function(){
    function slider(n){this.n=n; this.a=[];}
    slider.prototype.init=function(t,e,sec,m,o,k){
        var a=$(t), i=s=0, n=a.childNodes, l=n.length; this.s=k||0; this.m=m||0;
        for(i;i<l;i++){
            var v=n[i];
            if(v.nodeType!=3){
                this.a[s]={}; this.a[s].h=h=$(v).getElements(e)[0]; this.a[s].c=c=$(v).getElements(sec)[0];
                var trg = $(h).getElement('span.accArrow');
                if (SLICKMENU_ACC_EVENT<?php echo $id?> == 'mouseover') {
                    $(h).addEvents({
                        'mouseover' : new Function('event', 'event = new Event(event); event.stop();' + this.n+'.pr(0,'+s+')')
                    });
                } else {
                    if (trg) {
                        $(trg).addEvents({
                            'click' : new Function('event', 'event = new Event(event); event.stop(); ' + this.n+'.pr(0,'+s+')')
                        });
                    }
                }
                if(o==s){
                    $(h).addClass('oppened');
                    if(c){
                        c.style.height='auto';
                        c.style.visibility='visible';
                        c.d=1;
                    }
                }else{
                    if(c){
                        c.style.height=0;
                        c.style.visibility='hidden';
                        c.d=-1;
                    }
                }
                s++;
            }
        }
        this.l=s;
    };
    slider.prototype.pr=function(f,d){
        for(var i=0;i<this.l;i++){
            var h=this.a[i].h, c=this.a[i].c;
            if (c) {
                var k=c.style.height; 
                k=k=='auto' ? 1:parseInt(k);
                clearInterval(c.t);
                if((k!=1&&c.d==-1)&&(f==1||i==d)){
                    c.style.height='';
                    c.m=c.offsetHeight;
                    c.style.height=k+'px';
                    c.d=1;
                    $(h).addClass('oppened');
                    c.style.visibility='visible';
                } else if(k>0&&(f==-1||this.m||i==d)){
                    c.d=-1;
                    $(h).removeClass('oppened');
                }
                su(c);
            }
        }
    };
    function su(c){
        if (!SLICKMENU_ACC_ALLOW_ANIM<?php echo $id?>) {
            if (c.d == 1) {c.style.height='auto';} else {c.style.height='0px';}
        } else {
            c.t=setInterval(function(){sl(c)},SLICKMENU_ACC_ANIM_SPEED<?php echo $id?>);
        }
    };
    function sl(c){
        var h=c.offsetHeight, d=c.d==1?c.m-h:h; c.style.height=h+(Math.ceil(d/5)*c.d)+'px';
        if (SLICKMENU_ACC_ALLOW_OPACITY<?php echo $id?>) {c.style.opacity=h/c.m; c.style.filter='alpha(opacity='+h*100/c.m+')';}
        if((c.d==1&&h>=c.m)||(c.d!=1&&h==1)){if(c.d==1){c.style.height='auto'} else {c.style.visibility='hidden';} clearInterval(c.t);}
    };
    return{slider:slider};
}();

SlickMenu<?php echo $id?>.dropdown=function(){
    var z=50,s=6,a;
    function dd(n){this.n=n; this.h=[]; this.c=[];};
    dd.prototype.init=function(p,c) {
        a=c;
        var w=document.getElementById(p), s=w.getElementsByTagName('ul'), l=s.length, i=0;
        for(i;i<l;i++){
            var h=s[i].parentNode; this.h[i]=h; this.c[i]=s[i];
            $(h).addEvents({
                'mouseover': new Function('event', 'event = new Event(event); ' + this.n+'.st('+i+',true);'),
                'mouseout': new Function('event', 'event = new Event(event); ' + this.n+'.st('+i+');')
            });
        };
    };
    dd.prototype.st=function(x,f){
        var c=this.c[x], h=this.h[x], p=h.getElementsByTagName('a')[0];
        clearInterval(c.t);
        c.style.overflow='hidden';

        if(f){
            $(p).addClass(a);
            c.style.display='block';
            
            if(!c.mh){
                c.mh=c.offsetHeight;
                if (SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?>){
                    c.style.height=0;
                }
            }
            if(!c.mw){
                c.mw=c.offsetWidth;
                if (SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>){
                    c.style.width=0;
                }
            }
            if(c.mh==c.offsetHeight && c.mw==c.offsetWidth){
                c.style.overflow='visible';
            } else {
                c.style.zIndex=z; z++;
                c.t=setInterval(function(){sl(c,1);},SLICKMENU_DROP_ANIM_SPEED<?php echo $id?>);
            }
        } else {
            $(p).removeClass(a);
            c.t=setInterval(function(){sl(c,-1);},SLICKMENU_DROP_ANIM_SPEED<?php echo $id?>);
        }
    };
    function sl(c,f){
        var h=c.offsetHeight, w=c.offsetWidth, tostop = false;
        var pt = $(c).getStyle('paddingTop').toInt();
        var pb = $(c).getStyle('paddingBottom').toInt();
        if (pt || pb) h = h + ((pt + pb) * f);
        var pl = $(c).getStyle('paddingLeft').toInt();
        var pr = $(c).getStyle('paddingRight').toInt();
        if (pl || pr) w = w + ((pl + pr) * f);
        
        if (SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?> && SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>) {
            tostop=(((h<=0&&f!=1)||(h>=c.mh&&f==1))&&((w<=0&&f!=1)||(w>=c.mw&&f==1)));
        } else if (SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?>) {
            tostop=((h<=0&&f!=1)||(h>=c.mh&&f==1));
        } else if (SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>) {
            tostop=((w<=0&&f!=1)||(w>=c.mw&&f==1));
        }
        if (tostop){
            if(f==1){
                if (SLICKMENU_DROP_ALLOW_OPACITY<?php echo $id?>) {
                    c.style.filter='';
                    c.style.opacity=1;
                }
                c.style.overflow='visible';
            } else {
                c.style.display='none';
            }
            clearInterval(c.t);
            return;
        }
        
        var d=(f==1)?Math.ceil((c.mh-h)/s):Math.ceil(h/s);
        var dw=(f==1)?Math.ceil((c.mw-w)/s):Math.ceil(w/s);
        var o = 1;
        if (SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?>) {
            o=h/c.mh;
        } else if (SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>) {
            o=w/c.mw;
        }
        if (SLICKMENU_DROP_ALLOW_OPACITY<?php echo $id?>) {
            c.style.opacity=o;
            c.style.filter='alpha(opacity='+(o*100)+')';
        }
        if (SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?>){
            if ((h<=0&&f!=1)||(h>=c.mh&&f==1)) {
                c.style.height=c.mh+'px';
            } else {
                c.style.height=h+(d*f)+'px';
            }
        }
        if (SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>){
            if ((w<=0&&f!=1)||(w>=c.mw&&f==1)) {
                c.style.height=c.mh+'px';
            } else {
                c.style.width=w+(dw*f)+'px';
            }
        }
        if(!(SLICKMENU_DROP_ALLOW_HEIGHT<?php echo $id?> || SLICKMENU_DROP_ALLOW_WIDTH<?php echo $id?>)) {
            c.style.display='none';
        }
    };
    return{dd:dd};
}();
<?php

$js 
ob_get_contents();
ob_end_clean();

$js preg_replace('/[\n\t]/'''$js);
echo 
preg_replace('/\s{2,}/'' '$js);
?>