views_get_current_view performance
That function is just a wrapper for this function:
https://api.drupal.org/api/views/views.module/function/views_set_current_view/7.x-3.x
which will just return a reference to a static code cache. 

Conclusion: no view gets run, it's just grabbing a copy of what's already been created.

In general, views is very efficient in such cases.

But I'd tend to agree with @berramou that you might have a better way of accomplishing what you really, really want.