Db tuning is like tuning a car to run better on any road. Query optimization is like choosing better roads to drive. Storing in a cache is like putting things your a going after in the start of the road, so no need to drive the road.
It's like asking Are we there yet? - you can ask, but the distance won't change
Is just like driving in a car when the steer is on the opposite side and the seat is way too far.
Is just like fixing a car - you need to get to know the car first - gears, acceleration, lights, steer and so on.
- Try to find a person called John Doe The 2nd in 100 page paperback document.
- Imagine there would also be pages that tells in which pages you can find animals, fruits and persons. It might be faster to look in the person list, than looking into the animal list or just going over the whole document. That means making the right index for the right need.
I work a lot in cryptography; the most secure system would be unworkable for users and a system easiest for users would be too vulnerable. Tradeoffs.