c# – SQL查询在代码中比查询db direct需要更长的时间

我有一个SQL查询,在我使用SQL Management Studio时执行时间不到一秒,但是当我的代码执行它时,从数据库服务器获取结果需要30秒以上.结果包含1700行.另一个返回900行的类似查询需要几毫秒才能执行.这种奇怪行为的原因是什么？

public SqlDataReader ExecuteReader(string strSQL,ArrayList arParams)
    {
        OpenConnection();

        SqlCommand myCommand = new SqlCommand(strSQL,myConnection);
        myCommand.CommandTimeout = intTimeout;


        foreach (SqlParameter myParameter in arParams)
            myCommand.Parameters.Add(myParameter);

        return myCommand.ExecuteReader(System.Data.CommandBehavior.CloseConnection);
    }

STRSQL：

SELECT [Group].[Id],[Group].[intCustomerId],[Group].[strName],[Permission].[dtmCreated],[Permission].[intPermissionTypeId],[Permission].[intObjectTypeId],[Permission].[intObjectId],[Permission].[blnActive],[Permission].[blnHaveAccess],[Permission].[intLevelTypeId]             
 FROM [Group]
 LEFT JOIN Permission ON [Group].[Id] = intGroupId AND 
                         intObjectId = @ObjectId AND 
                         intObjectTypeId = @ObjectTypeId AND 
                         intLevelTypeId = @LevelType AND
                         intPermissionTypeId = @PermissionTypeId AND
                         blnActive = 1                                             
 WHERE [Group].[intCustomerId] = @CustomerId  AND
       [Group].[blnDeleted] = 0
 ORDER BY strName,blnActive DESC

arParams：

arParams.Add(DatabaseHandler.MakeSqlParameter("@CustomerId",customer.Id));
arParams.Add(DatabaseHandler.MakeSqlParameter("@ObjectId",masterprocess.Id));
arParams.Add(DatabaseHandler.MakeSqlParameter("@ObjectTypeId",Convert.ToInt32(ObjectType.MasterProcess)));
arParams.Add(DatabaseHandler.MakeSqlParameter("@PermissionTypeId",Convert.ToInt32(permissiontype)));
arParams.Add(DatabaseHandler.MakeSqlParameter("@LevelType",Convert.ToInt32(leveltype)));

DatabaseHandler.MakeSqlParameter：

public static SqlParameter MakeSqlParameter(String strName,int intInput)
{
    return new SqlParameter(strName,intInput);
}