the delete sql server procedure in my case to delete a scenario takes a long time to execute knowing that I have added indexes on the FK_Scenario, do you have a solution? ( the first two tables contain around 400 million rows )

My code :

DELETE FROM [ECRCPTA] WHERE [FK_Scenario] = @FK_Scenario        
DELETE FROM [EVTCNT] WHERE [FK_Scenario] = @FK_Scenario     
DELETE FROM  [FCEPAR] WHERE [FK_Scenario] = @FK_Scenario
DELETE FROM  [FCOBSQ] WHERE [FK_Scenario] = @FK_Scenario
DELETE FROM  [GARMVO] WHERE [FK_Scenario] = @FK_Scenario    
DELETE FROM  [MVTPMT] WHERE [FK_Scenario] = @FK_Scenario
DELETE FROM  [PROVEP] WHERE [FK_Scenario] = @FK_Scenario
DELETE FROM  [QUITTAN] WHERE [FK_Scenario] = @FK_Scenario
DELETE FROM  [RACHAT] WHERE [FK_Scenario] = @FK_Scenario

just the execution time is too long