If you want to require certain files explicitly on every request then you can use the 'files' autoloading mechanism. This is useful if your package includes PHP functions that cannot be autoloaded by PHP.
On the other hand classmap:
You can use the classmap generation support to define autoloading for all libraries that do not follow PSR-0/4. To configure this you specify all directories or files(as I've done above) to search for classes.
TL;DR: as currently specified, TwitterAPIExchange.php is being required/included on every page load whether it will be used or not.
should be:
Files documentation
On the other hand classmap:
TL;DR: as currently specified, TwitterAPIExchange.php is being required/included on every page load whether it will be used or not.