网站越来越慢，大家帮我看看数据库访问的代码有问题么？
我是C#初学者。任何方面的问题都有可能。

namespace   SimCity.Data
{
using   System;
using   System.Data;
using   System.Data.SqlClient;
///   <summary>
///   SqlHelper   的摘要说明。
///   </summary>
public   class   SqlHelper
{
public   SqlHelper()
{
}

public   static   void   ExecuteStoreProcedure(string   strConnection,   string   strStoredProcedure,   SqlParameter   []arParas,   out   int   nReturnValue)
{
SqlConnection   connection   =   new   SqlConnection(strConnection);
connection.Open();
SqlCommand   command   =   new   SqlCommand(strStoredProcedure,   connection);
if(arParas   !=   null   &&   arParas.Length   >   0)
{
foreach(SqlParameter   para   in   arParas)
{
command.Parameters.Add(para);
}
}
SqlParameter   parRet   =   command.Parameters.Add( "@returnvalue ",SqlDbType.NVarChar,30);
parRet.Direction   =   ParameterDirection.ReturnValue;
command.CommandType   =   CommandType.StoredProcedure;
command.ExecuteNonQuery();
command.Dispose();
connection.Close();
                        nReturnValue   =   (int)parRet.Value;
}

public   static   void   ExecuteStoreProcedure(string   strConnection,   string   strStoredProcedure,   SqlParameter   []arParas)
{
SqlConnection   connection   =   new   SqlConnection(strConnection);
connection.Open();
SqlCommand   command   =   new   SqlCommand(strStoredProcedure,   connection);
if(arParas   !=   null   &&   arParas.Length   >   0)
{
foreach(SqlParameter   para   in   arParas)
{
command.Parameters.Add(para);
}
}
command.CommandType   =   CommandType.StoredProcedure;
command.ExecuteNonQuery();
command.Dispose();
connection.Close();
}

public   static   DataSet   FillDataSet(string   strConnection,   string   strStoredProcedure,   SqlParameter   []arParas,   string   strTableName)
{
DataSet   dataset   =   null;

SqlConnection   connection   =   new   SqlConnection(strConnection);
dataset   =   new   DataSet();
connection.Open();

SqlDataAdapter   adapter   =   new   SqlDataAdapter();
SqlCommand   command   =   new   SqlCommand(strStoredProcedure,   connection);
if(arParas   !=   null   &&   arParas.Length   >   0)
{
foreach(SqlParameter   para   in   arParas)
{
command.Parameters.Add(para);
}
}
command.CommandType   =   CommandType.StoredProcedure;

adapter.SelectCommand   =   command;
adapter.Fill(dataset,   strTableName);

command.Dispose();
adapter.Dispose();
connection.Close();

return   dataset;
}
public   static   DataSet   FillDataSet(string   strConnection,   string   strStoredProcedure,   SqlParameter   []arParas,   out   int   nReturnValue)