Improve performance of multiple insert and update queries - sql

Question

I have two tables: Sale_Source (10.000 rows) and Sale_Target (1 billion rows). I have four queries to INSERT and UPDATE Sale_Target with the data from Sale_Source.
Source table has a nonclustered index on id and Date
Target table has indexes on id and Date but i have disable them to improve the Performance
Queries
INSERT query #1:
INSERT INTO dbo.Sale_Target (id, Salevalue, Salestring, Date)
SELECT id, Salevalue, Salestring, Date
FROM dbo.Sale_Source s
WHERE NOT EXISTS (SELECT 1 FROM dbo.Sale_Target t ON s.id = t.id)
UPDATE query #1 (when the date are the same):
UPDATE t
SET t.Salevalue = s.Salevalue,
t.Salestring = s.Salestring
FROM dbo.Sale_Source s
JOIN dbo.Sale_Target t ON t.id = s.id AND s.Date = t.Date
WHERE t.Salevalue <> s.Salevalue OR t.Salestring <> s.Salestring
UPDATE query #2 (when date on SaleSource > Date on SaleTarget):
UPDATE t
SET t.Salevalue = s.Salevalue,
t.Salestring = s.Salestring
FROM dbo.Sale_Source s
JOIN dbo.Sale_Target t ON t.id = s.id AND s.Date > t.Date
UPDATE query #3 (when id on Source is null in join clause):
UPDATE t
SET t.Salevalue = null,
t.Salestring = null
FROM dbo.Sale_Source s
LEFT JOIN dbo.Sale_Target t ON t.id = s.id
WHERE s.id IS NULL
The four queries require 1 hr. 30 mins. to finish, which is very slow for the source table with only 10.000 rows. I think the problem here is that each time when four queries run, they need to JOIN two source and target tables again, which cost a lot of time.
Therefore I have an idea:
I will create a query which saves the matched rows between two tables (source and target) into table temp_matched, and save the non matched rows (non matched to target) into temp_nonmatched.
For this, I have problem now with MERGE query because in MERGE we can't save data into another table.
Use temp_nonmatched in INSERT query, in UPDATE query. I will replace table Sale_Source with temp_matched.
Do you have any idea to do it or can we optimize these four queries in another way?
Thank you.
Table Definition:
CREATE TABLE [dbo].[Sale_Target](
[id] [numeric](8, 0) NOT NULL,
[Salevalue] [numeric](8, 0) NULL,
[Salestring] [varchar](20) NULL,
[Date] [Datetime2](7) NULL
) ON [PRIMARY]
CREATE NONCLUSTERED COLUMNSTORE INDEX "NCCI_Sale_Target"
ON [dbo].[Sale_Target] (id,Date)
CREATE TABLE [dbo].[Sale_Source](
[id] [numeric](8, 0) NOT NULL,
[Salevalue] [numeric](8, 0) NULL,
[Salestring] [varchar](20) NULL,
[Date] [Datetime2](7) NULL
) ON [PRIMARY]
CREATE NONCLUSTERED COLUMNSTORE INDEX "NCCI_Sale_Source"
ON [dbo].[Sale_Target] (id,Date)

Answer 1

Target Tables has no Index.
First thing I would do is index the Target Table on id and date.