Drill 2: The database is on fire

The situation

Database CPU sits at 90%. You check: 95% of queries are reads, and most of them fetch the same few thousand product pages. Web servers are at 20% CPU. Data size is a comfortable 40 GB.

What is the cheapest, most effective next step?

Why? Your reasoning in a sentence (optional)

How sure are you? Decide before you pick an answer.