Fine tune/Speed up my SQL stored procedure with currently take ~15-20mins

I need an expert to fine tune my stored procedure which I don't think is too complex. It tries to insert/update transactions/records in a master table only if it passes some rules. If it fails it insert/updates the transactions/records in another table. The procedure for 45,000 line takes around 15 mins. It works perfectly as is, but it takes so long and I know my tables in a couple of months will be +1million records so i'm nervous how long it will take then. -------------------------------------------------------------------- SQL SHELL EXAMPLE - Working one can be provided with test data -------------------------------------------------------------------- USE [CHAMP_DW] GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[ETL_stage_evestment_performance_to_champ] @BatchImportID UNIQUEIDENTIFIER OUTPUT AS BEGIN SET NOCOUNT ON; /*Variable Declaration*/ /*Assign static value for whole one time process*/ /*Create staging table so we can re-run procedure instead of having to rerun complete task again and again*/ -- POPULATE TEMP TABLE /*While loop started to get process record one by one*/ WHILE EXISTS(SELECT 1 FROM #stagingPerformance AS FHD WITH (NOLOCK)) BEGIN BEGIN TRY BEGIN TRANSACTION /*assign 1 record values to respective variables*/ /*Record wise validation start*/ SELECT @ErrorCode = NULLIF(STUFF(@ErrorCode,1,1,''),''), @ErrorMessage = NULLIF(STUFF(@ErrorMessage,1,1,''),'') IF @ErrorMessage IS NOT NULL BEGIN ;THROW 50552,'VALIDATION RAISE ERROR.',1 END /*Record wise validation end*/ -- INSERT/UPDATE FACT TABLE --COMMIT TRANSACTION END TRY BEGIN CATCH -- ROLL BACK -- INSERT/UPDATE LOG TABLE --COMMIT TRANSACTION END CATCH -- CLEAR VARIABLES END DROP TABLE #stagingPerformance END