Should I use CI for this task?

[eluser]term25[/eluser]
My client want to build a new website (he is using Drupal 7 right now) and now he has 1.5 million unique visitors a month (2.5 million impressions), so Drupal is kinda slow and not the best choice to continue working with... imho.

Should I decide for CI again or build a completely custom site including backend and frontend from scratch to save some performance?

Or should I try Laravel or something else (PHP version etc is not an issue, he has his own server)