I've been working more or less non-stop building all the vB customizations I've done over the years for XF. Most are just small little things, but in the end even small things take a bunch of PHP files when doing it MVC style. For example giving forums a default sort order requires 9 PHP files, 4 of which are listeners... so at a minimum it's adding 4 unique PHP being called for every page view and depending on how many models/template hooks are triggered, each of those are being called numerous times. By the time I'm done I'm probably going to have hundreds of Class Controller listeners alone... every page view is probably going to be including at least 500 unique PHP files, with a bunch of those being called multiple times. Maybe not a bad idea down the road to just grab all the enabled listeners and consolidate them into a single PHP file per listener type?