Well, actually you can. If you know that certain things are often used you can keep a list of them and force them into memory on the assumption that what you'll use this time you boot will be similar to what you used last time.
This is what the Windows process SuperFetch does (and why it is counterproductive to disable it).
I am quite familiar with Superfetch and how it works. I made a general statement to make a point. And Superfetch does have to access the data in question.