A WEB based app is by design an OLTP app.
You can never know how many users ar ehitting your DB.
Therefore you have to design your DB performance in view.
Your question is too generic to be able to answer it here but take into consideration your table and index design, also to load your huge CSV file you should use BCP with bulk logged recovery mode enabled.
Also as advice you should remove all the indexes from the table you are bcping in. After the load you can enable them.
But here take again care of your concurrent users!
Bye
Gabor