救一个方法.谢谢!

问题是.当打开一个面页时,如index.asp?id=1235时,面页运行的很快,
但当我这样时index.asp?id=12as时就运行很慢,返回要很长的时间,请问如何解决??谢谢.
<%
id=replace(trim(request("id"))," ","")
if not isNumeric(cint(request("id"))) then %>
<script language=javascript>
javascript:history.back()
</script>
<%end if
%>
<%set rs=server.CreateObject("ADODB.RecordSet")
sql="select * from companyid where downid="&id&""
rs.open sql,conn,1,1
if rs.eof or rs.bof then
%>
<script language=javascript>
javascript:history.back()
</script>
<%
else
company=rs("company")
bk=rs("bk")
rs.close
set rs=nothing
end if
%>