A Blender addon to manage linked files and proxies
This addon will allow you to add, remove, refresh, relocate all linked files in one simple UI. You can turn off a linked file and bring it back. You can also switch the linked file for a low res version and you have the possibility to turn on ho res rendering so that on screen you will only have the low res version but in final render it will render the ho res version.
Please see the following link for more information: