Optimize Code or Upgrade Memory?

Myself and my partners are building a very large online comparison site.

There are currently millions of products in the site and when we move to compare other things there could theoretically be 100 million or more.

The database is taking a hammering at the moment and the site keeps going down.

My partner is a tech nerd and wants to throw more hard drives and ram at it but i want him to optimize the code more.

Memory and ram is very cheap now so this is actually a good short term solution and we will need to upgrade eventually anyway.

My problem is that i personally think even though the memory and ram is a cheap solution we should spend the time to optimize the code a lot more even though this could cost many expensive hours of work combined to a few dollars for more ram.

What does Ycombinator think?