Script with 2000k listings

Hi Lancers, We have data of 2.4 million companies. We need a script (open source, custom or paid) that can 'handle' it. Meaning mysql is tuned, caching etc so the website will work fast. Because of the budget, only respond if you have done this before so it is easy and fast to do. If it works, you will be invited to tune our current big directories too. Good Luck bidding!