关于代码的性能，下面的代码中appendChild在谷歌浏览器性能好低，是什么原因
大家帮看看有些什么地方可以优化的，初学对象。。。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>JS对象</title></head><body><div id="moveId"> <label>表格行： <input name="textfield" type="text" size="10" id="tr" /> </label> 表格列： <input name="textfield2" type="text" size="10" id="td" /> <label> <input type="button" name="Submit" value="创建" id="btn"/> </label></div><script type="text/javascript">function Table(tr,td){ this.tr = tr; this.td = td;}Table.prototype.createTable = function(){ var st=(new Date()).getTime(); var tableHTML = "<table width=\"100%\" border=\"1\">"; for(var i=0;i<this.tr;i++){ tableHTML += "<tr>" for(var j=0;j<this.td;j++){ tableHTML +="<td bgcolor='" + bgcl() +"'>"+ rand(1,15) +"</td>"; } tableHTML += "</tr>" } tableHTML +="</table>" var cid = document.createElement("div"); cid.innerHTML = tableHTML; document.body.appendChild(cid);//性能低部分 cid = null; var st2=(new Date()).getTime() - st; alert(st2);}var rand = function(value1,value2){ return Math.floor(Math.random()*(value2-value1+1)+value1);}var bgcl = function(){ var r,g,b; r = rand(0,255).toString(16); g = rand(0,255).toString(16); b = rand(0,255).toString(16); r = r.length<2?"0"+r:r; g = g.length<2?"0"+g:g; b = b.length<2?"0"+b:b; //alert(); return "#"+r+g+b; }var btn = document.getElementById("btn"), tr = document.getElementById("tr"), td = document.getElementById("td"); btn.onclick = function(){ var reg = /^[1-9]\d*$/; if(!reg.test(tr.value)||!reg.test(td.value)){ alert("数据不合格"); }else{ var table1 = new Table(tr.value,td.value); table1.createTable(); } }bgcl();//alert(rand(1,15));</script></body></html>//我给你写一个随机颜色函数的高效版本var bgcl0 = ['','00000','0000','000','00','0'];function bgcl(){ var s = (Math.random()*0x1000000|0).toString(16), n=s.length; return "#"+ (n==6 ? s : (bgcl0[n] + s));}