为什么LINQ中的多个位置如此之慢？

Question

使用C＃和Linq to SQL，我发现我使用多个where的查询比使用单个where / and慢几个数量级。

这是查询

using (TeradiodeDataContext dc = new TeradiodeDataContext())
{
    var filterPartNumberID = 71;
    var diodeIDsInBlades = (from bd in dc.BladeDiodes
                            select bd.DiodeID.Value).Distinct();
    var diodesWithTestData = (from t in dc.Tests
                              join tt in dc.TestTypes on t.TestTypeID equals tt.ID
                              where tt.DevicePartNumberID == filterPartNumberID
                              select t.DeviceID.Value).Distinct();
    var result = (from d in dc.Diodes
                  where d.DevicePartNumberID == filterPartNumberID
                  where diodesWithTestData.Contains(d.ID)
                  where !diodeIDsInBlades.Contains(d.ID)
                  orderby d.Name
                  select d);
    var list = result.ToList();
    // ~15 seconds
}

但是，当最终查询中的条件为此时

where d.DevicePartNumberID == filterPartNumberID
& diodesWithTestData.Contains(d.ID)
& !diodeIDsInBlades.Contains(d.ID)
// milliseconds

它非常快。

在调用result之前比较ToList()中的SQL，这里是查询（手动添加值71代替@params）

-- MULTIPLE WHERE
SELECT [t0].[ID], [t0].[Name], [t0].[M2MID], [t0].[DevicePartNumberID], [t0].[Comments], [t0].[Hold]
FROM [dbo].[Diode] AS [t0]
WHERE (NOT (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM (
        SELECT DISTINCT [t2].[value]
        FROM (
            SELECT [t1].[DiodeID] AS [value]
            FROM [dbo].[BladeDiode] AS [t1]
            ) AS [t2]
        ) AS [t3]
    WHERE [t3].[value] = [t0].[ID]
    ))) AND (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM (
        SELECT DISTINCT [t6].[value]
        FROM (
            SELECT [t4].[DeviceID] AS [value], [t5].[DevicePartNumberID]
            FROM [dbo].[Test] AS [t4]
            INNER JOIN [dbo].[TestType] AS [t5] ON [t4].[TestTypeID] = ([t5].[ID])
            ) AS [t6]
        WHERE [t6].[DevicePartNumberID] = (71)
        ) AS [t7]
    WHERE [t7].[value] = [t0].[ID]
    )) AND ([t0].[DevicePartNumberID] = 71)
ORDER BY [t0].[Name]

和

-- SINGLE WHERE
SELECT [t0].[ID], [t0].[Name], [t0].[M2MID], [t0].[DevicePartNumberID], [t0].[Comments], [t0].[Hold]
FROM [dbo].[Diode] AS [t0]
WHERE ([t0].[DevicePartNumberID] = 71) AND (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM (
        SELECT DISTINCT [t3].[value]
        FROM (
            SELECT [t1].[DeviceID] AS [value], [t2].[DevicePartNumberID]
            FROM [dbo].[Test] AS [t1]
            INNER JOIN [dbo].[TestType] AS [t2] ON [t1].[TestTypeID] = ([t2].[ID])
            ) AS [t3]
        WHERE [t3].[DevicePartNumberID] = (71)
        ) AS [t4]
    WHERE [t4].[value] = [t0].[ID]
    )) AND (NOT (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM (
        SELECT DISTINCT [t6].[value]
        FROM (
            SELECT [t5].[DiodeID] AS [value]
            FROM [dbo].[BladeDiode] AS [t5]
            ) AS [t6]
        ) AS [t7]
    WHERE [t7].[value] = [t0].[ID]
    )))
ORDER BY [t0].[Name]

这两个SQL查询在SSMS中执行<1秒并产生相同的结果。

所以我想知道为什么第一个在LINQ方面较慢。令我担心的是因为我知道我在其他地方使用了多个where，却没有意识到这种严重的性能影响。

This question甚至已经回复了多个＆和哪里。而this answer甚至建议使用多个where子句。

任何人都可以解释为什么会发生这种情况吗？