Performance : Expose some important smarty configuration variables outside the smarty class

While working with multiple "complex" civicrm sites on dedicated server instances, I've noticed that even though the database was highly optimized, all sites were having some sort of overhead of nearly 1.5-2 seconds before rendering the results. That is on the contact display page, on search, advanced search and so on.
Added Redis caching to CiviCRM, helped with a bit of small improvement but again, the delay was there.
Digging deeper with XHProf, I've found out that for every page that was loading, Smarty was checking if the templates needed recompiling.

Long story short, inside the /packages/Smarty/Smarty.class.php there's a variable that is true by default: var $compile_check = true;
Description is the following:

This tells Smarty whether to check for recompiling or not. Recompiling does not need to happen unless a template or config file is changed. Typically you enable this during development, and disable for production.

Disabling this in production, i did see a big improvement in terms of speed, as Smarty is now being instructed not scan every time if it needs to recompile the templates.

My suggestion would be to expose that variable (along with $caching) as a constant so that for example we can add it to settings.php as 'false' in production environments.

I could provide a patch (if needed) that does that.

PS. "complex" = a CiviCRM instance with many extensions and many tpl injections through custom extensions.