Dropdown, Tagbox - Improve performance when working with large data sets

[JaneSjs]

When a data set contains a lot of items, Dropdown/Tagbox may not handle this well, for example, take more time to load items.

Introduce an option to improve the performance when using large datasets for Dropdown/Tagbox questions.

[JaneSjs]

The issue was discussed here:

• unable to access options title when using ajax request on select2 (paged content)
  There is too many options in my dataset (more than 100K) and dropdown can't load all of it at once. I had to use paginated version.
• Question: Select2 tagbox AJAX vs choicesByUrl
  ...there are times that the second dropdown above can have +1000 items and the type tagbox doesn't handle well that (the dropdown freezes and takes long time (+1 min) to load the results to the user)...