When programmatically adding views, what is a more efficient way to add them other than include them in mymodule.views_default.inc?
I'm not 100% sure if it'd help performance-wise, but it is possible to separate the Views into different files. In your case, this is probably useful anyway as that's a LOT of Views.

If you create a folder in your module called "views" (or whatever you want), then you can just add the following to your implementation of hook_views_default_views.

function MYMODULE_views_default_views() {
  $files = file_scan_directory(drupal_get_path('module', 'MYMODULE'). '/views', '/.view/');
  foreach ($files as $filepath =&gt; $file) {
    require $filepath;
    if (isset($view)) {
      $views[$view-&gt;name] = $view;
    }
  }
  return $views;
}


DISCLAIMER/CREDIT:

This code was taken from this blog post, and this comment, so make sure you pop over there and say thank you :)