How to load recentf only after opening/saving a file for the first time?

[Sebastien Vauban]

Hello,

Always with the same performance-oriented analysis of my .emacs file, I'm
trying to require recentf not during the startup, but later, as soon as it's
really needed. Not that heavy, but every little flow participate in the big
ocean...

I guess the right time to require recentf is the first time we open or save a
file.

Though, for opening, the only hook available is run after find-file, so too
late to save the first opened file, it seems.

What would be a correct way to delay the require of recentf?

Best regards,
Seb

-- 
Sebastien Vauban