Entity Framework自然是会比ADO.NET性能慢点，这个不多说了。直接上结果。
本该用测试项目的，不过我建了个aspx。下面是随便测20遍得到的结果
补充！！把12行改成 list = db.Role.AsNoTracking().ToList();
由于这只做查询，不需要上下文进行跟踪。效率瞬间提升平均3-5倍，超越SqlDataAdapter，（其实很多人用SqlDataAdapter而不是用SqlCommand）
测试代码（建aspx，nuget拿EF6.1dll，建数据库建表Role，自己插入6万条数据，有主键自增）
string connStr = "server=localhost;database=EF;uid=sa;pwd=your1234;Persist Security Info=True";
List<Role> list = new List<Role>();
DateTime start = DateTime.MinValue;
DateTime end = DateTime.MinValue;
Response.Write("查询6万条数据耗时测试 <br />");
using (var db = new DBContext(connStr))
{
start = DateTime.Now;
list = db.Role.ToList();
end = DateTime.Now;
Response.Write("EF6.1，耗时：" + (end - start).ToString() + " <br />");
}
start = DateTime.Now;
SqlConnection conn = new SqlConnection(connStr);
conn.Open();
SqlCommand cmd = new SqlCommand("select * from [Role]", conn);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
list.Add(new Role()
{
ID = dr.GetInt32(),
Name = dr.GetString(),
Desc = dr.GetString(),
CreateDate = dr.GetDateTime(),
ModifyDate = dr.GetDateTime()
});
}
dr.Close();
end = DateTime.Now;
Response.Write("ADO.NET SqlCommand + SqlDataReader，耗时：" + (end - start).ToString() + " <br />");
start = DateTime.Now;
SqlDataAdapter sda = new SqlDataAdapter("select * from [Role]", conn);
var ds = new DataSet();
sda.Fill(ds);
list = (from item in ds.Tables[].AsEnumerable()
select new Role
{
ID = item.Field<int>("ID"),
Name = item.Field<string>("Name"),
Desc = item.Field<string>("Desc"),
CreateDate = item.Field<DateTime>("CreateDate"),
ModifyDate = item.Field<DateTime>("ModifyDate"),
}).ToList();
conn.Close();
end = DateTime.Now;
Response.Write("ADO.NET SqlDataAdapter + DataSet，耗时：" + (end - start).ToString() + " <br />");
EF其实是不错的东西，楼主很喜欢；很多人说EF性能差，不过我觉得EF很利于开发进度。