Why choose faster than Set

I did 2 basic tests

1 -

Create Procedure [dbo].[SetLoop]
As Begin 
declare @counter int = 0 ,@a int,@b int,@c int,@d int,@e int
    While @counter < 1000000
    Begin
        set @a=1
        set @b=2
        set @c=3
        set @d=4
        set @e=5
        set @counter = @counter + 1
    End
End

create procedure SelectLoop
As Begin 
declare @counter int =0 ,@a int,@b int,@c int,@d int,@e int
    While @counter < 1000000
    Begin
        select @a=1, @b=2, @c=3, @d=4, @e=5,@counter = @counter + 1
    End
End

    var setTimes = new List<double>();
    for (var i = 0; i < 50; i++)
    {
        stopwatch.Start();
        dataContext.SetLoop();
        stopwatch.Stop();
        setTimes.Add(stopwatch.ElapsedMilliseconds);
        stopwatch.Reset();
    }

    var selectTimes = new List<double>();
    for (var i = 0; i < 50; i++)
    {
        stopwatch.Start();
        dataContext.SelectLoop();
        stopwatch.Stop();
        selectTimes.Add(stopwatch.ElapsedMilliseconds);
        stopwatch.Reset();
    }

    var setAverage = setTimes.Sum() / setTimes.Count;
    var selectAverage = selectTimes.Sum()/selectTimes.Count;

results

setAverage: 2418.44
selectAverage: 1037.52

setAverage: 2513.8
selectAverage: 1025.98

setAverage: 2496.52
selectAverage: 996.36

the average value of the result. Choose faster than specified in one and halfexactly142.78%

2 -

    While @counter < 1000000
    Begin
        select @a=1
        select @b=2
        select @c=3
        select @d=4
        select @e=5
        select @counter = @counter + 1
    End

    While @counter < 1000000
    Begin
        set @a=1
        set @b=2
        set @c=3
        set @d=4
        set @e=5
        set @counter = @counter + 1
    End

results

setAverage: 2518.58
selectAverage: 2504.44

setAverage: 2474.5
selectAverage: 2529.48

setAverage: 2511.22
selectAverage: 2514.04

mean they are the same

which means that if you need to set one variable, prefer to use Selectcuz in the future, if you want to set another one, it ,@w=3will only be added, but if you want to specify more than one variable defiantly, you need to use Select it easier to write, faster to execute

, Select , Set ?