How much difference is a cached query and a fresh one performance wise? I only have one client that could benefit because both of their sites draw heavy traffic, so i was thinking a query that can be called multiple times in a day that returns large result sets can be cached every morning and then the cache can feed the site throughout the day for use.

Is that the correct usage?

the site gets over 10k visits a day and each page visit is logged in the db. My queries against 7 million rows where their portion is about half bog the system down. I desperately need a way to speed this up.

Thanks in advance.