Temp Table VS physical Temp Tables in same db which one will be better for 30 gb data transformation.

Hello Experts,

I need your expertise, there is huge 30-200GB flat file (text) which I need to upload every week into sql Server. bulk copy statement being used to bring this data into sql table for Temporary use and then take this take and transform it accord to db schema and put into right tables.



Currently : data is brought into physical temporary table in same database and then ETL operation is being done. becuase data is huge like 30-200GB and then that temporary table gets deleted once job is over. so its a two step process.

I have two questions.
1. should I use DTS instead of bulk copy import and then ETL. I am trying to build the package which can do it in single step my questions is. As I know DTS is slower then bulk copy. How much benifit I will get reducing the one step and other hand implementing the slower process (DTS) when data is huge 30-200GB per week?

2. temporary tables (offered by sql server using #) also get stored in tempdb. is it ok to use temporary tables in custom db and import the data and then delete those tables. which is better use mircosoft offerd temp tables or custom tables and delete them later.

is there any performace gain.

what else I can do to improve the import process performance. normally now its talking 5-8 hours.